CHAPTER 3
Holland's Theory of Vocational Choice and Adjustment

MARGARET M. NAUTA

Illinois State University, Normal, IL

When John Holland introduced a theory of vocational choice in 1959, his goal was to present a framework that would be practical for counselors and clients to use. His work as a career counselor in educational, military, and clinical settings helped provide Holland with a sense of what was needed and what would be useful. He concluded that simplicity was critical—if a theory was too complex for counselors to explain and for clients to remember and reflect upon, it ran the risk of being underutilized. Therefore, Holland strove to articulate a theory that would be sufficiently robust to explain important outcomes and yet simple enough to be user‐friendly. It is safe to say he accomplished this goal with resounding success. Holland revised and refined his theory numerous times based on results from empirical studies he and others conducted to test elements of the theory. Now Holland's theory is generally regarded as among the most influential theories guiding career counseling and practice.

This chapter serves as an introduction to Holland's (1997) theory of vocational choice and is divided into three major sections:

1. An overview of the theory and its predictions.
2. A summary of research on the theory, including its applicability to diverse populations.
3. A discussion of how the theory can be applied to career issues that arise over the lifespan with diverse populations.

The chapter concludes with a series of take‐home messages that summarize for practitioners the key parts of the theory and their implications for career interventions.

OVERVIEW OF THE THEORY

The essence of Holland's theory is that both people and environments can be described in terms of their resemblance to six model, or theoretical, types. The interrelationships among the types provide the basis for several predictions about the kinds of careers people will choose, how satisfied they will be with their work, how well they will perform in their work, and the ease with which they will be able to make career decisions.

THE SIX TYPES OF PERSONS AND ENVIRONMENTS

According to Holland, by late adolescence most people can be characterized in terms of how closely they resemble each of six basic personality types: realistic, investigative, artistic, social, enterprising, and conventional (commonly abbreviated with the acronym RIASEC). Each type has a unique constellation of preferred activities, self‐beliefs, abilities, and values as summarized in Table 3.1. Readers are encouraged to consult Holland (1997) for more detailed descriptions of the personality types.

Describing how the RIASEC personality types develop was not a central goal of Holland, but he suggested they are likely the result of a complex interaction among “a variety of cultural and personal forces including peers, biological heredity, parents, social class, culture, and the physical environment” (Holland, 1997, p. 2). Based on these influences, Holland believed people first begin to prefer some activities over others, and then these preferences become strong interests and areas of competence that lead them to seek some experiences and to avoid others. This further reinforces their interests and abilities such that over time, the interests, areas of competence, and resulting self‐beliefs become dispositional and can be used to make predictions about people's future choices and behaviors.

In arguing for the presence of six basic types, Holland did not assert that people represent only a single type. Many individuals have a dominant type that they most closely resemble plus one or more additional types (called subtypes) that they also resemble to some degree. Accordingly, Holland recommended using the rank‐ordering of all six types to describe people. Considering all possible combinations of the rank‐ordered six types, there are 720 different personality profile patterns that can exist. Therefore, while providing simplicity by allowing us to think about individuals in terms of six dimensions, the theory actually allows for quite a bit of complexity and diversity among those individuals. In practice, many counselors use a three‐point code—called a Holland code—that is made up of the first letters of the three types a client most resembles. Thus, if a client most resembles the social type, but also shows a reasonable degree of resemblance to the artistic and enterprising types in descending order, he or she would have a Holland code of SAE.

TABLE 3.1 Characteristics of Holland's RIASEC Personality and Environment Types

Sources: Gottfredson, G. D., & Holland, J. L. (1996). Dictionary of Holland occupational codes (3rd ed.). Odessa, FL: Psychological Assessment Resources, Inc., Holland, J. L. (1997). Making vocational choices: A theory of vocational personalities and work environments (3rd ed.). Odessa, FL: Psychological Assessment Resources and Prediger, D. J. (1982). Dimensions underlying Holland's hexagon: Missing link between interests and occupations? Journal of Vocational Behavior, 48, 59–67.

Realistic Preference for working with: things Personality characteristics: frank, practical, focused, mechanical, determined, rugged Preferred/typical activities and skills: mechanical, manual, physical, and athletic tasks Sample careers: Fitness trainer, firefighter, mechanic, builder, farmer, landscaper Sample majors: criminal justice studies, athletic training, construction management Values: tradition, freedom, independence	Investigative Preference for working with: things and ideas Personality characteristics: analytical, intellectual, reserved, independent, ambitious Preferred/typical activities and skills: working with abstract ideas, solving intellectual problems, collecting data Sample careers: biologist, researcher, physician, mathematician, computer systems analyst Sample majors: botany, engineering, mathematics, pre‐med, food technology Values: independence, logic, achievement
Artistic Preference for working with: ideas and people Personality characteristics: complicated, original, impulsive, independent, expressive, creative Preferred/typical activities and skills: using imagination, creative expression Sample careers: artist, musician, actor, creative writer, photographer Sample majors: art, theater, graphic design, music Values: esthetic experience, self‐expression, imagination, non‐conformity	Social Preference for working with: people Personality characteristics: cooperative, helpful, empathic, kind, tactful, warm, sociable, generous Preferred/typical activities and skills: interacting with and helping people, teaching, guiding Sample careers: teacher, clergy, counselor, nurse, school bus monitor Sample majors: nursing, education, counseling, social work Values: altruism, ethics, equality
Enterprising Preference for working with: data and people Personality characteristics: persuasive, energetic, sociable, adventurous, ambitious, assertive Preferred/typical activities and skills: leading, managing, persuading, and organizing people Sample careers: manager, lawyer, business administrator, politician Sample majors: pre‐law, business management, political science Values: tradition, achievement, ambition	Conventional Preference for working with: data and things Personality characteristics: careful, conforming, conservative, responsible, controlled Preferred/typical activities and skills: ordering, attending to details Sample careers: accountant, banker, actuary, editor, office manager, librarian Sample majors: business, accounting Values: tradition, ambition, obedience, economic achievement, comfort

To assess a client's resemblance to the RIASEC types, counselors can use instruments developed by Holland and his colleagues, including the Vocational Preference Inventory (VPI; Holland, 1985b) and the Self‐Directed Search (SDS; Holland & Messer, 2013a). RIASEC scales have also been created for almost all major career interest inventories, including the Strong Interest Inventory (SII; Donnay, Morris, Schaubhut, & Thompson, 2005), the Unisex Edition of the ACT Interest Inventory (Swaney, 1995), and the Armed Services Vocational Aptitude Battery (U.S. Department of Defense, 2005) (see Hansen, Chapter 15, this volume). The U.S. Department of Labor's O*NET website contains a Holland‐based measure called the Interest Profiler (Lewis & Rivkin, 1999) that can be downloaded or completed online at no cost. These instruments provide RIASEC interest scores, which are more narrowly defined than are the broader RIASEC type scores from the SDS (which include information about other personal attributes, in addition to interests), but, in practice, interest and type scores are usually used in the same way. In addition, the RIASEC dimensions serve as the organizing framework for instruments measuring other career‐relevant constructs, such as people's beliefs about their abilities (e.g., the Skills Confidence Inventory; Betz, Borgen, & Harmon, 2004).

Holland proposed that, like people, work and educational environments can also be categorized in terms of their resemblance to the six RIASEC types. Each environment type presents unique opportunities and tends to require different skills of its incumbents (see Table 3.1). Readers can consult Gottfredson and Holland (1996) and Holland (1997) for more complete lists and detailed descriptions of the environment types. As with people, some environments are quite complex and resemble multiple RIASEC types, so again the rank‐ordering of multiple types is useful, and three‐point Holland codes are often used to describe environments as well.

One way to determine an environment's type is on the basis of the personalities of the people working in it because, as Holland explained, “Where people congregate, they create an environment that reflects the types they most resemble” (Holland, 1997, p. 3). Thus, an environment comprising mostly workers with CRE personalities would be considered a CRE environment. Alternatively, an environment can be described based on the types of activities in which people in it usually engage. The Position Classification Inventory (PCI; Gottfredson & Holland, 1991) allows employees or supervisors to rate the frequency with which a job involves various activities, values, and perspectives that are grouped by RIASEC type. Holland codes are also available for hundreds of occupations in the Dictionary of Holland Occupational Codes (DHOC; Gottfredson & Holland, 1996); ancillary materials to the SDS, such as the Occupations Finder (Holland & Messer, 2013b) and Educational Opportunities Finder (Messer, Holland, & PAR Staff, 2013); and in many other sources of occupational information, including the O*NET database (see Gore & Leuwerke, Chapter 19, this volume).

PREDICTIONS BASED ON RELATIONSHIPS AMONG THE TYPES

In striving for a theory that was simple enough to be widely used, Holland willingly sacrificed some detail and predictive power. He maintained that a more complex theory with more than six types or more constructs would be impractical. Nevertheless, Holland recognized that it was important to acknowledge the limits of the theory and to place it in context. Therefore, he introduced his theory with an “other things being equal” (1997, p. 12) qualifier, explaining that the theory is useful for understanding individuals' career choices after controlling for age, gender, social class, and other influences that limit opportunities or the range of careers a person can or does consider. A variety of barriers can constrain people's freedom to make career choices (see Blustein & Duffy, Chapter 7, and Lent, Chapter 5, this volume), and Holland's theory best accounts for the choices people make when they perceive they have options and from within the range of options they perceive as viable. The theory, however, does not preclude a counselor from exploring barriers to client options and helping clients develop strategies to manage or overcome identified barriers.

After the influence of other factors has been accounted for, Holland suggested that the interrelationships among the RIASEC personality and environment types allow us to make several predictions about people's career choices, satisfaction, and performance. Four important constructs related to these predictions are congruence, differentiation, consistency, and identity.

Congruence.  The most important part of Holland's theory is the idea that an individual's personality is better suited to some environments than to others. He asserted that people search for and enter environments that permit them to “exercise their skills and abilities, express their attitudes and values, and take on agreeable problems and roles” (p. 4). In other words, people seek environments that fit well with their personalities. Environments also seek good‐fitting employees via their recruitment and selection of people with desired characteristics. Thus, like the “theory of work adjustment” (Dawis, 2000; Swanson & Schneider, Chapter 2, this volume), Holland's theory is an exemplar of the person–environment fit approach.

Holland used the term congruence to refer to the degree of fit between an individual and his or her current or projected environment with respect to the RIASEC types. The more similar the personality is to the environment, the more congruent are the two. A person with an RIA personality working in an RIA environment has a very high level of congruence. That same individual working in an RIE environment would have slightly lower congruence, and that person in an SEC environment would have a very low degree of congruence.

Congruence has been operationalized in many different ways in research and practice. The simplest measure considers only the match between the first letters of the person's and the environment's Holland codes, whereas other congruence indices consider the rank ordering of two or more personality and environment types (see Brown & Gore, 1994; Nye, Prasad, Bradburn, & Elizondo, 2018; Wille, Tracey, Feys, & De Fruyt, 2014; Young, Tokar, & Subich, 1998, for summaries and evaluations of congruence indices).

Holland theorized that congruence is a determinant of several important outcomes, including people's career aspirations and choices, work satisfaction, job stability, and performance. Specifically, he predicted that:

• People will tend to aspire to and choose educational and work environments that are congruent with their personalities.
• When people are in environments that are highly congruent with their personalities, they will be more satisfied and successful, and they will remain in those environments longer, resulting in greater stability (i.e., fewer job changes) over the lifespan.

Differentiation.  A minority of people and environments resemble one RIASEC type almost exclusively (i.e., are “pure” types), whereas other people and environments are similar to many of the types. Holland used the term differentiation to describe the degree to which a person or environment is clearly defined with respect to the RIASEC types.

People with high levels of differentiation show a strong resemblance to one RIASEC type and little resemblance to other types, whereas people with low levels of differentiation have similar degrees of resemblance to many of the types. The lowest degree of differentiation is present in the profile of a person who receives identical scores on all six RIASEC scores when taking an inventory such as the SDS. Holland operationalized differentiation as the difference between a person's highest and lowest scores on the six types. Other differentiation indices, for example, the distance between the highest and lowest scores that comprise a person's three‐point Holland code, have also been used (for descriptions of several differentiation indices, see Alvi, Khan, & Kirkwood, 1990; Tracey, Wille, Durr II, & De Fruyt, 2014).

Highly differentiated work environments have employees and activities that clearly align with one RIASEC type and few of the others. An example is an auto repair shop in which all of the employees are primarily engaged in hands‐on, mechanical work that exemplifies the realistic type, even though some may specialize in electronic systems, others in body work, and still others in engine repair. Environments made up of employees with varied RIASEC types or that require many different kinds of work activities have low levels of differentiation. An example is a medical office complex in which there are physicians (primary I type), nurses (primary S type), and medical records clerks (primary C type), whose work activities can be quite disparate. Work environment differentiation can be quantified by having employees or supervisors rate the environment using the PCI and then using indices that are analogous to those used to calculate personality differentiation.

Holland theorized that differentiation has implications for the process of career decision‐making and that it moderates the relationships between congruence and its outcomes. People with highly differentiated personalities should be drawn to a narrow range of occupational areas with which there is obvious congruence. On the other hand, people with highly undifferentiated personalities can have difficulty making career decisions because they feel torn between multiple areas that are equally attractive (or equally unappealing, in the case of low, undifferentiated personality profiles). Likewise, because highly differentiated environments are more predictable (i.e., are easier to identify and involve more activities typically associated with a given type), they should more easily attract highly congruent employees. Accordingly, Holland predicted that:

• Personality differentiation is positively associated with ease of career decision‐making. Therefore, individuals with highly undifferentiated personalities may struggle to a greater degree with making career choices.
• The positive relationships between congruence and work satisfaction, success, and stability will be stronger when differentiation (either personality, environmental, or both) is greater.

Consistency.  Each RIASEC type, whether personality or environment, has more in common with some types than with others. When examining the pattern of correlations among RIASEC scores, Holland, Whitney, Cole, and Richards (1969) discovered a roughly circular ordering of types and subsequently presented what has become an icon in career development and assessment: The Holland Hexagon (see Figure 3.1).

FIGURE 3.1 Holland's hexagonal model of the relationships among personality and environment types.

From Holland, J. L., Whitney, D. R., Cole, N. S., & Richards, J. M., Jr. (1969). An Empirical Occupational Classification Derived from a Theory of Personality and Intended for Practice and Research (ACT Research Report No. 29). Iowa City: American College Testing Program. Copyright 1969 by the American College Testing Program. All rights reserved. Reproduced with permission from ACT, Inc.

As shown by the correlations among the RIASEC type scores in Figure 3.1, when the RIASEC types are placed, in order, on the points around a hexagon, those on adjacent points (e.g., I and A) are generally more similar to one another than are those that are more distant from one another (e.g., I and S). Those that are diametrically opposed (e.g., I and E) usually share the least in common. This underlying structure, or calculus—in which the RIASEC types are equidistantly located around the hexagon and there is an inverse relationship between distances on the hexagon and similarity—provides a means for determining the degree to which there is relative harmony versus discordance among the types a person or environment most closely resembles.

When the types that make up a person's or environment's Holland code are adjacent on the hexagon (i.e., are more similar), the person or environment has a high degree of what Holland called consistency. For instance, the social and enterprising types, while having distinct characteristics, share a common element of involving work with people (Prediger, 1982). A low level of consistency is present when the types making up a person's or environment's Holland code are diametrically opposed (e.g., I and E) and have little in common. For example, a highly inconsistent work environment is one that requires a combination of interests and abilities that are rarely required in the same job and that few people will have. Consistency is frequently calculated by examining the position of the first two letters of the three‐letter person or environment Holland code on the hexagon, although more complex methods for determining consistency have also been used (see Strahan, 1987; Tracey et al., 2014).

Among both people and environments, consistency is more the norm than the exception. For example, the DHOC lists only two occupations as having the highly inconsistent ACS Holland code, whereas over 80 are listed that have the highly consistent CER Holland code. As a result, people with more consistent personalities will be able to consider and choose from more occupations that allow them to express most of the key elements of their personalities. Similarly, highly consistent environments should be able to recruit from a larger pool of employees with highly congruent personalities. Accordingly, Holland predicted that:

• Consistency is positively associated with ease of career decision‐making. People with highly inconsistent personalities may be more challenged when attempting to find highly congruent environments.
• Consistency moderates the relationships between congruence and its outcomes. The relationships between congruence and work satisfaction, performance, and stability will be stronger when consistency (either personality, environmental, or both) is high.

Identity.  Finally, Holland noted that some people and environments are more clearly defined and have more stability over time than do others. Identity refers to the degree to which a person has “a clear and stable picture of one's goals, interests, and talents” (Holland, 1997, p. 5) and can be assessed using the Identity Scale of My Vocational Situation (MVS; Holland, Daiger, & Power, 1980), the Vocational Identity Status Assessment (Porfeli, Lee, Vondracek, & Weigold, 2011), or the vocational identity measure (Gupta, Chong, & Leong, 2015). Strong environmental identity is present when an environment or organization has clear, integrated goals, tasks, and rewards that are stable over long time intervals. A work setting with a limited range of highly related positions that remain the same over time would have a strong, or crystallized, identity, whereas a work setting with varied positions that change frequently has a more diffuse identity. Holland indicated that one way to operationalize environmental identity is to take the inverse of the number of occupations within a work setting. A small business with employees in four different occupations—such as salesperson, marketing executive, administrative assistant, and product designer—would have an identity of .25 (the inverse of 4).

Theoretically, identity is strongly related to differentiation and consistency because people or environments with high degrees of differentiation and consistency are expected to have more clear and stable goals. In fact, Holland considered identity to be somewhat redundant with differentiation and consistency, but he thought identity provides a more direct measure of “how well a person defines himself or herself” (1997, p. 33).

As with differentiation and consistency, Holland expected that:

• A stronger, well‐defined identity promotes ease of career decision‐making.
• Identity moderates the relationships between congruence and its outcomes. Specifically, congruence will have stronger positive relationships with work satisfaction, stability, and performance when identity (either of the person, the environment, or both) is well‐defined.

SUMMARY

In summary, when all else is equal, Holland predicted that individuals who have highly consistent and differentiated personality profiles should have more crystallized identities, make career decisions with greater ease, and experience greater stability in their career trajectories. Those with less differentiated, less consistent profiles may have more diffuse identities and may struggle more with career decision‐making and have less stable career paths. He expected that people will seek environments that are congruent with their personalities, and when they do so, they will “probably do competent work, be satisfied and personally effective, and engage in appropriate social and educational behavior” (Holland, 1997, p. 40). Likewise, environments characterized by a high degree of consistency and differentiation and that possess a clear identity are expected to have employees with higher levels of satisfaction, stability, and productivity.

RESEARCH SUPPORT FOR HOLLAND'S THEORY

Holland's theory consists of easily quantifiable constructs and predictions that lend themselves well to scientific investigation. Consequently, hundreds of studies examining aspects of Holland's theory have been conducted. We now know a great deal about many parts of the theory, including its applicability to diverse populations. Several meta‐analyses (Assouline & Meir, 1987; Nye, Su, Rounds, & Drasgow, 2012; Tracey & Rounds, 1993; Tsabari, Tziner, & Meir, 2005) and reviews of the empirical status of Holland's theory (e.g., Carson & Mowsesian, 1993; Holland, 1997; Nauta, 2010; Spokane, 1985) provide a more in‐depth analysis of this body of research. Some of the larger trends are summarized here.

RESEARCH ON THE TYPES AND THEIR INTERRELATIONSHIPS

Much research has been devoted to verifying that the RIASEC types exist among people and environments and that they possess the characteristics described by Holland (1997). Researchers have also tested the degree to which the types and their interrelationships are invariant (or similar) across different segments of the population.

Existence of the types.  Because Holland's theory relies upon six types as the basis for matching people to environments, it has been critical to establish that the RIASEC types do, in fact, exist. Numerous studies have provided evidence that people's self‐descriptions (e.g., on adjective checklists or interest inventories) cluster together in ways that resemble Holland's types. This has been shown to be true among a wide variety of individuals, including middle school students (Sung, Cheng, & Wu, 2016), high school students (e.g., Holland, 1962), college students (e.g., Edwards & Whitney, 1972), and working adults (e.g., Rachman, Amernic, & Aranya, 1981). There is also support for the existence of the types among environments, because workers' and job analysts' descriptions of workplace requirements and rewards often group together in ways that resemble the RIASEC types when subjected to factor or cluster analyses (e.g., Donnay & Borgen, 1996; Rounds, Smith, Hubert, Lewis, & Rivkin, 1999). Of course, documenting the presence of the RIASEC types does not mean this is the only structure or valid mechanism for categorizing persons and environments, but Holland's six types do seem to provide a reasonable heuristic for doing so.

Links to personality.  Holland (1997) conceptualized the RIASEC types as reflections of people's personalities, which raises interesting questions about how the types might relate to traits in basic personality taxonomies, such as those in the Big Five personality model (McCrae & Costa, 1987; see Rottinghaus, Park, & Washington, Chapter 18, this volume for a description of the Big Five personality types). Generally, the RIASEC types appear to be related to, but not redundant with, basic personality traits (e.g., Mount, Barrick, Scullen, & Rounds, 2005). In particular, meta‐analyses (Barrick, Mount, & Gupta, 2003; Larson, Rottinghaus, & Borgen, 2002) show positive associations between extraversion and both social and enterprising types and between openness to experience and both artistic and investigative types. There also may be positive associations between agreeableness and social interests and between conscientiousness and conventional interests (Larson et al., 2002), but these associations have been found less consistently.

Basic personality traits can help provide a more nuanced understanding of people's RIASEC profiles. For instance, a person's level of agreeableness may help explain a tendency toward more social versus enterprising types, as those high in agreeableness tend to score higher on the social type (Costa, McCrae, & Holland, 1984). Additionally, some personality traits relate to profile elevation, or the magnitude of people's interests (Darcy & Tracey, 2003). Those who are high in openness to experience tend to have higher absolute levels of interests across all RIASEC types than do those who are lower in openness, whereas neuroticism tends to have an inverse association with the magnitude of people's interests (Ackerman & Heggestad, 1997; Holland, Johnston, & Asama, 1994; Holtrop, Born, & de Vries, 2015).

Relations to other constructs.  Many studies have linked people's RIASEC scores with scores on measures of other constructs, and the findings have tended to be fairly consistent with Holland's descriptions of the types. For example, RIASEC scores are related in ways that are consistent with Holland's type descriptions to people's values (Leuty & Hansen, 2013; Williams, 1972) and life goals (Astin & Nichols, 1964), as well as to measures of actual or perceived ability (e.g., Ackerman & Heggestad, 1997; Betz, Harmon, & Borgen, 1996). RIASEC environment types have characteristics that are consistent with Holland's descriptions (Maurer & Tarulli, 1997), although there has been less research on the environment types than on the personality types. Overall, Holland's framing of the model RIASEC types as broad constructs (i.e., collections of interests and other attributes, like values and abilities) seems well‐founded.

Stability over time.  Holland's conceptualization of the RIASEC personality types as being dispositional by late adolescence has also been critical to verify empirically. After all, it would be of little practical value to use the RIASEC types as the basis for seeking congruent future environments if people's resemblance to those types fluctuates tremendously. Studies have documented a good degree of stability for RIASEC type scores for late adolescents and adults over fairly short time periods. For example, the test–retest stability of RIASEC scores on the SDS for a sample that included high school students, college students, and adults ranged from .76 to .89 over periods of up to 12 weeks (Holland et al., 1994).

A larger body of literature has examined the stability of RIASEC interests (again, just one component of the Holland types) as assessed by instruments such as the SII. Because some of these studies have used lengthier follow‐up intervals, they provide more useful information about the degree to which RIASEC scores can be considered trait‐like. Consistent with Holland's dispositional view, findings from their meta‐analysis of interest stability research led Low, Yoon, Roberts, and Rounds (2005) to conclude that RIASEC interests are reasonably stable between the ages of 12 and 40 and are comparable to personality traits and abilities in terms of their level of stability. Interests do appear to become more stable across adolescence (Xu & Tracey, 2016) and become noticeably more stable after the age of 18 (Low et al., 2005). Across studies that assessed RIASEC interests using retest periods of over 1 year, Low and colleagues found that realistic and artistic interests tended to be more stable over time than did enterprising and conventional interests, but all the types exhibited sufficient stability to support the practice of RIASEC interest assessment in career counseling. Nevertheless, it is important to note that some individuals' interests change substantially over time (see Swanson, 1999). Holland (1997) explained such fluctuations in terms of inconsistent, undifferentiated profiles or a more diffuse identity, but as will be discussed later these explanations have received only mixed support.

Group differences.  There are some reliable differences in RIASEC score levels across segments of the population. The largest of these differences is with respect to gender. On many measures, women tend to outscore men on the social, artistic, and conventional types, and men score higher than do women on the realistic and investigative types (Su, Rounds, & Armstrong, 2009). Gender differences on the social and realistic types are particularly pronounced (Su et al., 2009; Xu & Tracey, 2016). Differences by Racial/ethnic group tend to be fairly small in size. One study found that Asian Americans scored higher on measures of the investigative type than did members of other Racial/ethnic groups (Fouad, 2002), but most other studies (e.g., Fouad & Mohler, 2004) have not found such differences. The gender and Racial/ethnic group differences in RIASEC scores probably reflect the different kinds of experiences and opportunities people have as they are growing up (Holland, 1997), and comparisons of birth cohorts from the mid‐1970s to the mid‐2000s suggest gender differences on some of the RIASEC types are getting smaller in magnitude over time (Bubany & Hansen, 2011), paralleling the trend in the United States toward viewing gender in more egalitarian and less stereotypical ways. Differences in RIASEC score levels by age appear to be fairly small, but the scores of adolescents do appear to be more variable and less differentiated than those of adults (Ion, Nye, & Iliescu, 2019).

The structure of types.  A good deal of research has investigated the degree to which Holland's hexagon provides a good representation of the relationships among the RIASEC types. Not surprisingly, given that the hexagon figure was articulated on the basis of known correlations among RIASEC type scores, findings from many studies have generally supported the RIASEC ordering of types among people and environments. That is, types that are adjacent on the hexagon have consistently been found to be more strongly related than are nonadjacent types (e.g., Armstrong & Rounds, 2008; Darcy & Tracey, 2007). However, because there is less support for the fit of a strict model that specifies equal distances between the points of the hexagon (e.g., Armstrong, Hubert, & Rounds, 2003), many writers (e.g., Armstrong & Rounds, 2008; Darcy & Tracey, 2007) now refer more generally to a RIASEC circular ordering, or “circumplex,” rather than to a hexagonal structure per se.

With a few exceptions (e.g., Rounds & Tracey, 1996), most studies have found that the fit of the RIASEC circumplex in mostly U.S. samples is either invariant or varies to a fairly small degree based on gender and race/ethnicity (Armstrong et al., 2003; Darcy & Tracey, 2007; Kantamneni, 2014; Rounds & Tracey, 1993; Ryan, Tracey, & Rounds, 1996) and socioeconomic status (Ryan et al., 1996). Gender differences in the RIASEC structure may be more pronounced among individuals who are Racial/ethnic minorities (Armstrong, Fouad, Rounds, & Hubert, 2010; Kantamneni & Fouad, 2011), however.

The RIASEC model has been tested in samples from across the globe. Data from some samples (e.g., Morgan & de Bruin, 2018; Yang, Morris, & Protolipac, 2018) support the circumplex model, but in other studies' samples (e.g., Glosenberg, Tracey, Behrend, Blustein, & Foster, 2019; Rounds & Tracey, 1996) the model does not fit well. At this point there appears to be little discernable pattern to the kinds of non‐Western cultures and nationalities for whom the structural model fits well versus poorly, except that the fit may be better in societies with higher levels of economic development (Glosenberg et al., 2019), and the model's fit is particularly in question for people in Asian countries (e.g., Armstrong & Rounds, 2008; Rounds & Tracey, 1996; Sung et al., 2016; Yang, Stokes, & Hui, 2005). Asian Americans and residents of Asian countries have also been found to exhibit lower levels of congruence with anticipated and chosen occupations than other Racial/ethnic groups (Fouad & Mohler, 2004; Gupta & Tracey, 2005; Leong, Austin, Sekaran, & Komarraju, 1998). Finally, the circumplex model does not fit well in younger (elementary and middle school) samples (Iliescu, Ispas, Ilie, & Ion, 2013; Lent, Tracey, Brown, Soresi, & Nota, 2006; Sung et al., 2016). Based on this pattern of findings, counselors should be cautious when using the hexagon framework to interpret RIASEC scores with younger adolescents and those residing in some other countries, particularly in Asia. Otherwise the framework seems to work well.

RESEARCH TESTING HOLLAND'S PREDICTIONS ABOUT WORK‐RELATED OUTCOMES

Another critical area of research has examined the validity of Holland's predictions about work‐related outcomes on the basis of his theory's constructs. Of these, Holland's predictions about outcomes associated with congruence have received the most attention.

Congruence in relation to choice, satisfaction, and performance.  There is good evidence that RIASEC type and interest scores are predictive of many individuals' choices of college majors and careers (see Betz, 2008; Holland, 1997). That is, people frequently choose majors and careers that are congruent with their dominant RIASEC type(s). Congruence with respect to the RIASEC types is also predictive of people's persistence or stability in college majors and occupations (e.g., Donohue, 2006; Kristof‐Brown, Zimmerman, & Johnson, 2005; Tracey & Robbins, 2006). Moreover, people who change jobs often switch to ones that are more congruent with their personalities than the ones they left (Oleski & Subich, 1996). These findings all support Holland's basic assumption that people seek environments with which their personalities are congruent. Nonetheless, some occupations have employees whose RIASEC interests are quite heterogeneous (Borgen & Lindley, 2003; Nye, Perlus, & Rounds, 2018). For example, the dominant Holland type among people who are satisfied chiropractors and investment managers is distributed fairly evenly across all six types (Nye, Perlus, et al., 2018), so it should not be assumed that people in a given occupation all have a particular Holland code.

Meta‐analyses have also supported Holland's prediction that person–environment congruence with respect to the RIASEC types is associated with favorable work‐related outcomes. Congruence is positively associated with job and academic satisfaction (Assouline & Meir, 1987; Nye, Prasad, et al., 2018; Spokane, Meir, & Catalano, 2000; Tsabari et al., 2005) and performance (Kristof‐Brown et al., 2005; Nye et al., 2012; Nye, Prasad, et al., 2018; Nye, Su, Rounds, & Drasgow, 2017; Spokane et al., 2000; Tsabari et al., 2005). The sizes of these effects range substantially across studies but are generally small or moderate in magnitude, however. For example, the correlation between congruence and job satisfaction in both the Tsabari et al. (2005) and Tranberg, Slane, and Ekeberg (1993) meta‐analyses was .17, and corrected correlations between congruence and job performance in meta‐analyses have ranged from .15 (Van Iddekinge, Roth, Putka, & Lanivich, 2011) to .36 (Nye et al., 2012).

Methodological limitations of studies and narrow samples may partially explain the modest relationships between congruence and work‐related outcomes, but clearly congruence should be considered only one of many factors that predict important work‐related outcomes. In addition, congruence logically relates to some aspects of work‐related outcomes more so than others. As would be theoretically expected, congruence is more strongly associated with employees' satisfaction with their work activities (i.e., intrinsic job satisfaction) than with their satisfaction with their job security and salary (i.e., extrinsic job satisfaction) (Ishitani, 2010). Also, whereas congruence may explain people's performance levels on specific work activities, it would not be expected to explain more general aspects of work performance, such as whether someone arrives to work on time.

Differentiation and consistency.  Holland's differentiation and consistency hypotheses have received less attention than have those regarding congruence, and from the studies that have examined differentiation and consistency as predictors of work‐related outcomes (see Carson & Mowsesian, 1993), there is mixed empirical support. In fact, Holland (1985a) characterized this body of findings as “checkered” because there have been both positive and negative findings. Even among the studies that have found support for Holland's predictions that differentiation and consistency are predictive of career decision‐making ease, career choice stability, and work satisfaction, the relationships tend to be fairly small in magnitude. However, in recent research that operationalized consistency and differentiation using sophisticated indices that consider all six types and the relative differences between them (Tracey et al., 2014), the researchers obtained stronger support for the constructs' utility in predicting career outcomes, or as moderators of the associations between congruence and outcomes, so the jury is still out.

Identity.  Holland's predictions about vocational identity's positive associations with differentiation and consistency, career decision‐making ease, career stability, and performance have been addressed in only a handful of empirical studies, perhaps because this construct was only added to later versions of the theory. As with the findings regarding differentiation and consistency, the pattern of findings regarding identity is best described as “checkered.” The hypothesized positive associations of identity to consistency and differentiation were not supported in some studies (Gottfredson & Jones, 1993; Leung, Conoley, Scheel, & Sonnenberg, 1992) and have been positive but weak in others (Hirschi, 2010; Hirschi & Läge, 2007; Im, 2011). Having a stronger identity does seem to be associated with some benefits such as readiness to make career decisions (Hirschi & Läge, 2007), career decision‐making self‐efficacy (Gushue, Scanlan, Pantzer, & Clarke, 2006), and satisfaction with chosen academic majors (Cox, Bjornsen, Krieshok, & Liu, 2016), but other studies (Blinne & Johnston, 1998; Leung, 1998) have yielded mixed or null results regarding the relation of vocational identity to predicted outcomes. Environmental identity was linked to job satisfaction in one study (Perdue, Reardon, & Peterson, 2007) but otherwise has received little empirical attention.

SUMMARY

In summary, there is empirical support for many aspects of Holland's theory. The presence of the RIASEC types has been well‐documented, and the interrelationships of types appear to be fairly consistent across major segments of the U.S. population, although the generalizability of the RIASEC model to those of Asian and other nationalities is less clear. RIASEC type or interest scores contribute substantially to the prediction of people's choices of college majors and careers, and congruence with respect to the RIASEC types is also associated with the stability of those choices. Congruence is positively related to work satisfaction and performance, but the magnitude of those relationships is not as substantial as Holland might have believed it would be. Support for Holland's predictions involving the secondary constructs of consistency, differentiation, and identity is less robust.

APPLICATIONS OF THE THEORY

When evaluating theories with respect to the degree to which they help career counselors and clients in practice, Holland's (1997) theory is unsurpassed, as it serves as the guiding framework for more career interventions than any other theory (Brown, 2002).

CONTRIBUTIONS TO OCCUPATIONAL CLASSIFICATION AND CAREER ASSESSMENT

There is little doubt that Holland's theory has helped to transform the practice of career counseling. Prior to the theory's introduction, clients could take an interest inventory and receive scores that reflected their similarity to employees in various occupations. The challenge for counselors, however, was to help clients understand how those occupations fit together in some coherent way and to extrapolate beyond the limited number of occupations represented on the inventory itself. Holland's theory allows us to think about people and environments using a manageable number of dimensions, thereby facilitating clients' understanding of themselves and the world of work. In addition, Holland's instruments for assessing the RIASEC personality types, the introduction of RIASEC scales on major interest inventories (e.g., Campbell & Holland, 1972), and the development of parallel RIASEC environmental classification materials (e.g., the DHOC) have greatly improved clients' and counselors' ability to generate fairly comprehensive lists of possible careers that warrant consideration.

Because of this user‐friendliness, Holland's theory has been widely adopted. It serves as the organizing framework for many self‐help systems, such as the best‐selling What Color is your Parachute? (Bolles, 2018). Holland's SDS and its supporting materials were designed for self‐administration and interpretation, which has contributed to the theory's widespread use in educational and career workshops and in computer‐assisted career guidance programs (see Harris, 2013). Finally, Holland's theory frequently guides individual career counseling interventions (see Brown & Ryan Krane, 2000).

From the perspective of Holland's theory, career intervention involves using the RIASEC typology to characterize a client's personality in order to understand how she or he may best fit with the world of work. Typically, this is done using the SDS or an interest inventory that has RIASEC scales, although counselors can also gather information about a client's resemblance to the RIASEC types using a clinical interview. In such an interview, the counselor helps the client verbalize and explore her or his preferred activities, perceived competencies, self‐beliefs, interests, values, and occupational daydreams. The counselor then explains Holland's model to the client, and together they work to determine the client's resemblance to each of the types. Regardless of the way in which the assessment occurs, an interpretation typically focuses on determining the client's Holland code. The client can then use environmental classification materials to explore environments with which his or her personality is fairly congruent. Counselors can also use the constructs of differentiation, consistency, and identity to help clients understand sources of career decision‐making difficulties and identify possible ways to reduce those difficulties. In general, counseling is intended to “create self‐understanding and stimulate more insightful and constructive planning” (Holland, 1997, p. 199).

Using this general framework, counselors can address many kinds of client needs, including helping people who are seeking to make or remake educational or career choices, preparing people to implement career choices, promoting greater career/work satisfaction and performance, and promoting optimum career development among younger persons. The manner in which counselors who use Holland's theory might address each of these concerns is discussed next.

WORKING WITH PERSONS WHO ARE SEEKING TO MAKE OR REMAKE EDUCATIONAL OR CAREER CHOICES

Because it provides a parallel way for conceptualizing people and environments, Holland's theory is optimally suited for assisting people who are seeking to make initial or subsequent educational or career choices. Once a client's Holland code is known, a counselor can assist the client in consulting the Occupations Finder, the Educational Opportunities Finder, the DHOC, the O*NET database, or other environmental classification materials to explore occupations that are congruent. Because, at least after adolescence, RIASEC type scores tend to be fairly stable for most people, and because congruence is associated (albeit modestly) with work satisfaction and performance, the rationale for using this approach to match people to environments is solid.

When using Holland's theory as the basis for identifying potentially satisfying educational and work environments, it is important for clients and counselors not to use the theory in a more simplistic manner than it was intended. Several points are worth keeping in mind.

• First, a work environment need not be completely congruent with a client's personality to be rewarding. While occupations with Holland codes that are dramatically different from the client's personality might be tentatively eliminated in order to allow for greater focus in career exploration, exploration for most clients would ideally be inclusive of occupations with several Holland codes. For example, a client with an ASI personality would be encouraged to consider and explore occupations with Holland types of all combinations of the ASI types (e.g., ASI, AIS, SAI, SIA), particularly if there is not a high degree of differentiation in the person's profile (i.e., if the scores are not spread very far apart). Also, although in practice it is common to use three‐point person and environment Holland codes, Holland recommended using the rank‐ordering of all six types as part of an analysis of congruence. Depending on the degree to which the client also resembles types beyond the tertiary type, additional categories of occupations (e.g., ASE) may also be recommended for exploration. Moreover, there may be value in exploring with a client the nature of her or his dislikes with respect to RIASEC types, as work activities people are averse to are associated with job dissatisfaction (Phan & Rounds, 2018).
• Second, although congruence is positively associated with favorable work‐related outcomes, the strength of these associations is modest. Clearly, congruence can be an important determinant of work satisfaction for some people, but it is essential for counselors and clients to view congruence with respect to the RIASEC types as only one of many sources of information when matching clients to environments. RIASEC congruence might best help clients understand the kinds of educational or work environments whose inhabitants will share the most in common with them or in which they will enjoy the typical work activities (Ishitani, 2010). Constructs from other theories, such as the theory of work Adjustment (see Swanson & Schneider, Chapter 2, this volume), would be an appropriate supplement to help clients explore environments that would provide a match for their needs and values.
• Third, socialization and real or perceived barriers may have contributed to clients having had limited experiences in areas that are non‐traditional for persons of their race (Fouad & Kantamneni, Chapter 10, this volume) or gender (Schultheiss, Chapter 9, this volume). This would be reflected on inventories such as the SDS in terms of lower RIASEC raw scores for those non‐traditional areas. A counselor would ideally work with a client to assess whether her or his inventoried RIASEC scores accurately reflect her or his authentic self. When it appears that external constraints may have impeded development in some areas that would be intrinsically rewarding, the counselor could then attempt to broaden career possibilities by helping the client to consider how these barriers might be bypassed or how areas of potential interest might be reconsidered (for example, see the modified occupational card sort described by Lent, Chapter 5, this volume).
• Fourth, Holland's “other things being equal” qualifier is particularly important when working with clients who have constrained educational or career options due to economic reality, family wishes, and other barriers. In one sense, Holland's theory is limited because it assumes that people are relatively free to choose environments based on RIASEC congruence, an assumption that clearly does not hold for all clients. On the other hand, the theory is quite flexible because it paints a picture of people and environments using broad strokes (the RIASEC types). Although a person may not have many degrees of freedom in options from which to choose, the theory suggests that maximizing congruence will be beneficial, so choosing from among the most congruent of available options would be advocated. Because occupations with varied prerequisites (e.g., levels of needed training or education) are present within each RIASEC type, maximizing RIASEC congruence may still be a consideration even when there are limited options from which to choose. Helping clients with limited options identify and remove barriers to congruent but currently unattainable options may be a way to help them expand their occupational possibilities.

For some clients who are seeking to make educational or career choices, engaging in self‐exploration and environmental exploration and identifying congruent environments may be a sufficient intervention. For others, Holland's secondary constructs of differentiation, consistency, and identity may be particularly useful to consider. Increasing personality differentiation and helping to define more clearly the client's identity are common goals of counseling interventions if the client lacks direction as a result of feeling torn between multiple areas of comparable appeal. Helping clients achieve greater personality differentiation by gaining more varied experiences to learn what they like and dislike may be helpful in some cases, particularly when clients learn new information that disconfirms assumptions they may have held about occupations (Moore, Neimeyer, & Marmarosh, 1992).

Using counseling sessions to explore in more depth the areas of comparable strength of interest may also yield additional information that helps clients prioritize some areas over others. Occupational card sorts, such as the Missouri Occupational Card Sort (Krieshok, Hansen, Johnston, & Wong, 2002), with Holland code classifications for various job titles, may assist a client in exploring and articulating what it is about each RIASEC type that is appealing or unappealing. Because negative affect (e.g., depression) can contribute to a low, undifferentiated RIASEC profile, counselors might screen for and treat mood disorders that suppress a client's interests or perceived competencies. Finally, addressing negative ways of thinking, and promoting career concern, control, curiosity, and confidence (dimensions of career adaptability; see Savickas, Chapter 6, this volume), may be of some benefit to clients, as dysfunctional career thoughts (Dipeolu, Sniatecki, Storlie, & Hargrave, 2013; Galles & Lenz, 2013; Jo, Ra, Lee, & Kim, 2016) and career adaptability (Negru‐Subtirica, Pop, & Crocetti, 2015; Porfeli & Savickas, 2012) have consistently been linked to vocational identity clarity.

Promoting consistency is not typically a goal of career counseling, but Holland's consistency construct may be useful in counseling nevertheless. First, some clients may simply experience a sense of normalization when a counselor points to a highly inconsistent personality profile as a source of career decision‐making difficulties. Likewise, clients with inconsistent personalities may feel conflicted about their current or future career plans, and their ambivalence can be validated by acknowledging both the pros and cons of having diverse interests.

Second, although clients with highly inconsistent personality profiles may experience frustration to find that few environments are highly congruent with their personalities, counselors can help such clients think creatively about ways to create new career options or tweak existing options in order to maximize congruence. For example, environments with the highly inconsistent AC combination may be rare, but a client could brainstorm ways to maximize exposure to activities that involve the orderly and systematic manipulation of data (C activities) within a traditionally A environment, say, by cataloging and inventorying materials in an art library. For other clients, it may be helpful to recognize that although expressing highly inconsistent parts of one's personality may be difficult in a single job, taking on temporary work, combining part‐time jobs, or making planned, periodic career changes can be legitimate options for some persons (Donnay et al., 2005). Finally, clients with inconsistent profiles can be encouraged to find other, perhaps avocational, outlets for parts of their personalities that are likely to be unexpressed through work. The Leisure Activities Finder (Messer, Greene, Kovacs, & Holland, 2013)—an ancillary to the SDS that provides Holland codes for hobbies, sports, and other activities—may be useful toward this end.

PROMOTING WORK SATISFACTION AND PERFORMANCE

Another important application of Holland's theory involves working with people who want to experience greater job satisfaction and/or performance. Satisfaction and performance are clearly different outcomes, but because Holland's predictions about sources of work satisfaction and success are the same, interventions targeting these outcomes are nearly identical. The primary hypothesis from the perspective of Holland's theory is that a person who is dissatisfied and/or underperforming in work may either have made a career choice that was incongruent with his or her personality in the first place, or else there was a shifting of the primary RIASEC types within the person or the environment such that a once congruent career choice is no longer so. The latter would not be uncommon if, for example, the typical activities of a workplace changed after the introduction of some new technology.

As a first step, a counselor would gather information to assess the degree of RIASEC congruence between the client and his or her current work environment in order to test the low‐congruence hypothesis. Because some work environments are quite complex or can be idiosyncratic, it is wise not to rely exclusively on existing environmental classifications (e.g., the DHOC) to determine the three‐letter Holland code of the client's current environment. Rather, it is preferable to have the client estimate the time spent in various activities and to see if the person is in a special subunit that can be isolated and assessed (Holland, 1997). It may also be useful to have clients complete the PCI as a way to develop a RIASEC code for their current jobs. Discussing the RIASEC types and the idea of congruence with a client may provide him or her with a framework with which to think about dissatisfaction/underperformance that may provide some new clarification and insight.

If the low‐congruence hypothesis is supported, there are several options. The least intrusive option—and a reasonable first step to explore with a client—is to consider the possibility of tweaking the work environment so that it is more congruent with the client's personality. In many work settings there is some flexibility in how employees complete their jobs. A client could be encouraged to ask a supervisor about the possibility of shifting responsibilities or taking on some new responsibilities that would increase congruence.

Subunits within an occupation can have different Holland codes because they comprise employees with different types or emphasize different activities. For example, although according to the DHOC the Holland code of the typical administrative assistant is ESC, within a large organization, some administrative assistants may have frequent direct contact with the public, whereas other administrative assistants' primary responsibilities involve little face‐to‐face contact with others and relatively greater emphasis on recording data. The former subunit would likely be more congruent with a client who has a strong resemblance to the social type. Thus, it is possible for a client to move toward greater congruence without changing careers altogether. If such changes to the environment are unlikely or unappealing to the client, then a goal of counseling might be to explore other careers or jobs that might provide a better match, again using RIASEC environmental classification materials.

Theoretically, because Holland hypothesized stronger congruence–satisfaction and congruence–performance relations under conditions of high consistency, differentiation, and identity, working to promote a client's sense of identity may also be valuable, although the research support for these hypotheses is not strong. Nonetheless, for a client with a very low degree of personality differentiation or a poorly defined identity, there might be merit in promoting greater self‐understanding and differentiation as a way of increasing the probability of shifting to a career that is more congruent. On the other hand, it is important to keep in mind the modest strength of congruence–satisfaction and congruence–performance relationships. RIASEC congruence is one consideration, but a counselor would wisely explore other sources of job satisfaction and performance as well (see Lent & Brown, Chapter 23, this volume).

HELPING PEOPLE IMPLEMENT CAREER CHOICES

Holland's theory has the most direct applicability for working with clients to identify educational or career choices, but it also has some implications for helping people implement those choices. The primary goal of a counselor who is using Holland's theory to work with a client who is ready to implement a career choice is to identify and remove any barriers that would impede congruence‐seeking. Such barriers could be external, such as when family disapproval makes it difficult for a client with a highly differentiated artistic personality to enter an artistic work environment; or they could be internal, as when low confidence contributes to a client's reluctance to attend a job interview for a highly congruent position. It is also important to help clients identify and build support for their primary career option and implementation efforts. Indeed, meta‐analyses have revealed that support building efforts are critical ingredients of successful choice‐making (Brown & Ryan Krane, 2000) and job finding (Liu, Huang, & Wang, 2014) interventions.

Holland's theory may also be applicable to the implementation of career choices by providing clients with a framework for describing to potential employers how their abilities and characteristics map onto the position employers are seeking to fill. For example, discussing transferrable skills from a previous position may be easier when clients have a mechanism, such as the RIASEC types, for understanding the links between a previous and prospective work environment.

PROMOTING OPTIMUM CAREER DEVELOPMENT AMONG CHILDREN AND ADOLESCENTS

The choice‐making and choice‐implementing applications described in the earlier text are primarily relevant for work with late adolescents or adults. Indeed, this is the population for whom Holland's theory is the primary target, and given that RIASEC type and interest scores are less stable in younger adolescents, using RIASEC scores to narrow career choice considerations with younger people is ill‐advised. Nevertheless, Holland's theory can be useful when working with younger adolescents to the degree that it provides them with a rationale for learning as much as possible about themselves and the world of work.

A counselor might help a younger client begin to think about himself or herself and the world of work in RIASEC terms and encourage her or him to seek opportunities related to each of the RIASEC areas, even if some areas do not hold much initial appeal. Conceptually, knowing which RIASEC types one does not closely resemble is important in the development of personality differentiation and a clear vocational identity. In addition, research has shown that thinking about career interests in terms of the RIASEC model is associated with career decision‐making benefits, presumably because it helps people understand the career information that exists and enables them to use it better in their decision‐making (Tracey, 2008). Thus, interventions with younger persons might introduce them to the RIASEC framework so that they can use it as a schema within which to incorporate new information they acquire about themselves and the world of work.

CONCLUSIONS AND PRACTICE IMPLICATIONS

Holland's theory provides a straightforward means for classifying personalities and work environments. The following tips for practitioners summarize the ways in which the theory is commonly and most optimally applied.

• Practitioners seek to promote optimum career development by encouraging clients to learn as much as possible about themselves and work environments. By educating clients about Holland's theory and the RIASEC types, counselors give clients a parallel way for thinking about themselves and the world of work.
• Counselors assess clients' resemblance to the RIASEC types using a clinical interview, the SDS or VPI, and/or an interest inventory that has RIASEC scales.
• Using environmental classification resources, such as the DHOC, the Educational Opportunities Finder, or the O*NET database, counselors may assist clients in identifying potentially congruent educational and work environments. Obviously incongruent environments might be tentatively ruled out in order to help clients home in on a few areas that are potentially satisfying and in which they are likely to perform well. Ideally, the generation of educational and career possibilities should, however, be inclusive, involving not only environments with Holland codes that match the client's personality identically but also those with similar Holland codes.
• RIASEC congruence is associated with favorable work‐related outcomes, including job satisfaction and performance, but not strongly so. Congruence can, therefore, be considered as one source of information, yet counselors must also work hard to help clients consider other sources of satisfaction and performance. Highly congruent occupations certainly warrant consideration but without the sense that they are specifically being prescribed by the counselor.
• Clients who are experiencing career decision‐making difficulties may benefit from interventions designed to promote personality differentiation and the crystallization of vocational identity. Such interventions might involve gaining more experiences in diverse areas and prioritizing areas of interest via discussion and exploration, addressing negative career thoughts, and promoting career adaptability.
• Clients with highly inconsistent personalities may need avocational outlets for expressing parts of their personalities because there will be few environments that will be highly congruent with all parts of their personalities. Alternatively, such clients might need to be creative in modifying existing positions in order to emphasize parts of themselves that are not well‐represented in the environment or may simply plan to change careers in the future in order to use parts of themselves that are not well‐expressed in an initial choice.
• Once clients have identified career choices, Holland's theory supports the practice of removing real or perceived barriers and building social supports in order to promote the seeking of congruent work positions.

REFERENCES

1. Ackerman, P. L., & Heggestad, E. D. (1997). Intelligence, personality, and interests: Evidence for overlapping traits. Psychological Bulletin, 121, 219–245. doi:10.1037/0033‐2909.121.2.219
2. Alvi, S. A., Khan, S. B., & Kirkwood, K. J. (1990). A comparison of various indices of differentiation for Holland's model. Journal of Vocational Behavior, 36, 147–152. doi:10.1016/0001‐8791(90)90022‐T
3. Armstrong, P. I., Fouad, N. A., Rounds, J., & Hubert, L. (2010). Quantifying and interpreting group differences in interest profiles. Journal of Career Assessment, 18, 115–132. doi:10.1177/1069072709354367
4. Armstrong, P. I., Hubert, L., & Rounds, J. (2003). Circular unidimensional scaling: A new look at group differences in interest structure. Journal of Counseling Psychology, 50, 297–308. doi:10.1037/0022‐0167.50.3.297
5. Armstrong, P. I., & Rounds, J. B. (2008). Vocational psychology and individual differences. In S. D. Brown & R. W. Lent (Eds.), Handbook of counseling psychology (4th ed., pp. 375–391). New York, NY: Wiley.
6. Assouline, M., & Meir, E. I. (1987). Meta‐analysis of the relationship between congruence and well‐being measures. Journal of Vocational Behavior, 31, 319–332. doi:10.1016/0001‐8791(82)90036‐7
7. Astin, A. W., & Nichols, R. C. (1964). Life goals and vocational choice. Journal of Applied Psychology, 48, 50–58. doi:10.1037/h0048653
8. Barrick, M. R., Mount, M. K., & Gupta, R. (2003). Meta‐analysis of the relationship between the five‐factor model of personality and Holland's occupational types. Personnel Psychology, 56, 45–74. doi:10.1111/j.1744‐6570.2003.tb00143.x
9. Betz, N. E. (2008). Advances in vocational theories. In S. D. Brown & R. W. Lent (Eds.), Handbook of counseling psychology (4th ed., pp. 357–374). New York, NY: Wiley.
10. Betz, N. E., Borgen, F. H., & Harmon, L. W. (2004). Skills Confidence Inventory. Mountain View, CA: CPP, Inc.
11. Betz, N. E., Harmon, L. W., & Borgen, F. H. (1996). The relationships of self‐efficacy for the Holland themes to gender, occupational group membership, and vocational interests. Journal of Counseling Psychology, 43, 90–98. doi:10.1037/0022‐0167.43.1.90
12. Blinne, W. R., & Johnston, J. A. (1998). Assessing the relationships between vocational identity, academic achievement, and persistence in college. Journal of College Student Development, 39, 569–576.
13. Bolles, R. N. (2018). What color is your parachute? 2019: A practical manual for job‐hunters and career‐changers (Rev. Ed.). New York, NY: Ten Speed Press.
14. Borgen, F. H., & Lindley, L. D. (2003). Individuality and optimal human functioning: Interests, self‐efficacy, and personality. In W. B. Walsh (Ed.), Counseling psychology and optimal human functioning (pp. 55–91). Hillsdale, NJ: Lawrence Erlbaum.
15. Brown, C. (2002). Career counseling practitioners: Reflections on theory, research, and practice. Journal of Career Development, 29, 109–127. doi:10.1023/A:1019916203761
16. Brown, S. D., & Gore, P. A. (1994). An evaluation of interest congruence indices: Distribution characteristics and measurement properties. Journal of Vocational Behavior, 45, 310–327. doi:10.1006/jvbe.1994.1038
17. Brown, S. D., & Ryan Krane, N. E. (2000). Four (or five) sessions and a cloud of dust: Old assumptions and new observations about career counseling. In S. D. Brown & R. W. Lent (Eds.), Handbook of counseling psychology (3rd ed., pp. 740–766). New York: Wiley & Sons.
18. Bubany, S. T., & Hansen, J. C. (2011). Birth cohort change in the vocational interests of female and male college students. Journal of Vocational Behavior, 78, 59–67. doi:10.1016/j.jvb.2010.08.002
19. Campbell, D. P., & Holland, J. L. (1972). A merger in vocational interest research: Applying Holland's theory to Strong's data. Journal of Vocational Behavior, 2, 353–376. doi:10.1016/0001‐8791%2872%2990012‐7
20. Carson, A. D., & Mowsesian, R. (1993). Moderators of the prediction of job satisfaction from congruence: A test of Holland's theory. Journal of Career Assessment, 2, 130–144. doi:10.1177/106907279300100203
21. Costa, P. T., McCrae, R. R., & Holland, J. L. (1984). Personality and vocational interests in an adult sample. Journal of Applied Psychology, 69, 390–400. doi:10.1037/0021‐9010.69.3.390
22. Cox, D. W., Bjornsen, A. L., Krieshok, T. S., & Liu, Y. (2016). Occupational engagement and academic major satisfaction: Vocational identity's mediating role. The Career Development Quarterly, 64, 169–180. doi:10.1002/cdq.12049
23. Darcy, M., & Tracey, T. J. G. (2003). Integrating abilities and interests in career choice: Maximal versus typical assessment. Journal of Career Assessment, 11, 219–237. doi:10.1177/1069072703011002007
24. Darcy, M. U. A., & Tracey, T. J. G. (2007). Circumplex structure of Holland's RIASEC interests across gender and time. Journal of Counseling Psychology, 54, 17–31. doi:10.1037/0022‐0167.54.1.17
25. Dawis, R. V. (2000). The person‐environment tradition in counseling psychology. In W. E. Martin, Jr. & J. L. Swartz‐Kulstad (Eds.), Person‐environment psychology and mental health (pp. 91–111). Mahwah, NJ: Erlbaum.
26. Dipeolu, A., Sniatecki, J. L., Storlie, C. A., & Hargrave, S. (2013). Dysfunctional career thoughts and attitudes as predictors of vocational identity among young adults with attention deficit hyperactivity disorder. Journal of Vocational Behavior, 82, 79–84. doi:10.1016/j.jvb.2013.01.003
27. Donnay, D. A. C., & Borgen, F. H. (1996). Validity, structure, and content of the 1994 Strong Interest Inventory. Journal of Counseling Psychology, 43, 275–291. doi:10.1037/0022‐0167.43.3.275
28. Donnay, D. A. C., Morris, M. L., Schaubhut, N. A., & Thompson, R. C. (2005). Strong interest inventory manual. Mountain View, CA: CPP, Inc.
29. Donohue, R. (2006). Person‐environment congruence in relation to career change and career persistence. Journal of Vocational Behavior, 68, 504–515. doi:10.1016/j.jvb.2005.11.002
30. Edwards, K. J., & Whitney, D. R. (1972). Structural analysis of Holland's personality types using factor and configural analysis. Journal of Counseling Psychology, 19, 136–145. doi:10.1037/h0032637
31. Fouad, N. A. (2002). Cross‐cultural differences in vocational interests: Between‐group differences on the Strong Interest Inventory. Journal of Counseling Psychology, 49, 283–289. doi:10.1037/0022‐0167.49.3.282
32. Fouad, N. A., & Mohler, C. J. (2004). Cultural validity of Holland's theory and the Strong Interest Inventory for five Racial/ethnic groups. Journal of Career Assessment, 12, 423–439.
33. Galles, J. A., & Lenz, J. G. (2013). Relationships among career thoughts, vocational identity, and calling: Implications for practice. The Career Development Quarterly, 61, 240–248. doi:10.1002/j.2161‐0045.2013.00052.x
34. Glosenberg, A., Tracey, T. J. G., Behrend, T. S., Blustein, D. L., & Foster, L. L. (2019). Person‐vocation fit across the world of work: Evaluating the generalizability of the circular model of vocational interests and social cognitive career theory across 74 countries. Journal of Vocational Behavior, 112, 92–108. doi:10.1016/j.jvb.2019.01.002
35. Gottfredson, G. D., & Holland, J. L. (1991). The Position Classification Inventory: Professional manual. Odessa, FL: Psychological Assessment Resources.
36. Gottfredson, G. D., & Holland, J. L. (1996). Dictionary of Holland occupational codes (3rd ed.). Odessa, FL: Psychological Assessment Resources, Inc.
37. Gottfredson, G. D., & Jones, E. M. (1993). Psychological meaning of profile elevation in the Vocational Preference Inventory. Journal of Career Assessment, 1, 35–49. doi:10.1177/106907279300100105
38. Gupta, A., Chong, S., & Leong, F. T. L. (2015). Development and validation of the vocational identity measure. Journal of Career Assessment, 23, 79–90. doi:10.1177/1069072714523088
39. Gupta, S., & Tracey, T. J. G. (2005). Dharma and interest‐occupation congruence in Asian Indian college students. Journal of Career Assessment, 3, 320–336.
40. Gushue, G. V., Scanlan, K. R. L., Pantzer, K. M., & Clarke, C. P. (2006). The relationship of career decision‐making self‐efficacy, vocational identity, and career exploration behavior in African American high school students. Journal of Career Development, 33, 19–28. doi:10.1177/0894845305283004
41. Harris, B. J. (2013). Computer‐assisted career guidance systems: A part of NCDA history. The Career Development Quarterly, 61, 181–185. doi:10.1002/j.2161‐0045.2013.00047.x
42. Hirschi, A. (2010). Individual predictors of adolescents' vocational interest stabilities. International Journal for Educational and Vocational Guidance, 10, 5–19. doi:10.1007/s10775‐009‐9171‐2
43. Hirschi, A., & Läge, D. (2007). Holland's secondary constructs of vocational interests and career choice readiness of secondary students: Measures for related but different constructs. Journal of Individual Differences, 28, 205–218. doi:10.1027/1614‐0001.28.4.205
44. Holland, J. L. (1959). A theory of vocational choice. Journal of Counseling Psychology, 6, 35–45.
45. Holland, J. L. (1962). Some explorations of a theory of vocational choice: I. One‐and‐two‐year longitudinal studies. Psychological Monographs: General and Applied, 76, 1–49. doi:10.1037/h0093823
46. Holland, J. L. (1985a). Making vocational choices: A theory of vocational personalities and work environments. Englewood Cliffs, NJ: Prentice Hall.
47. Holland, J. L. (1985b). Manual for the vocational preference inventory. Odessa, FL: Psychological Assessment Resources, Inc.
48. Holland, J. L. (1997). Making vocational choices: A theory of vocational personalities and work environments (3rd ed.). Odessa, FL: Psychological Assessment Resources.
49. Holland, J. L., Daiger, D. C., & Power, P. G. (1980). My Vocational Situation. Palo Alto, CA: Consulting Psychologists Press.
50. Holland, J. L., Johnston, J. A., & Asama, N. F. (1994). More evidence for the relationship between Holland's personality types and personality variables. Journal of Career Assessment, 2(4), 331–340. doi:10.1177/106907279400200401
51. Holland, J. L., & Messer, M. A. (2013a). Self‐directed search form R (5th ed.). Lutz, FL: PAR.
52. Holland, J. L., & Messer, M. A. (2013b). The occupations finder. Odessa, FL: PAR.
53. Holland, J. L., Whitney, D. R., Cole, N. S., & Richards, J. M. (1969). An empirical occupational classification derived from a theory of personality and intended for practice and research (ACT research report no. 29). Iowa City, IA: American College Testing Program.
54. Holtrop, D., Born, M. P., & de Vries, R. E. (2015). Relating the spherical representation of vocational interests to the HEXACO personality model. Journal of Vocational Behavior, 89, 10–20. doi:10.1016/j.jvb.2015.04.003
55. Iliescu, D., Ispas, D., Ilie, A., & Ion, A. (2013). The structure of vocational interests in Romania. Journal of Counseling Psychology, 60, 294–302. doi:10.1037/a0032199
56. Im, S. (2011). The effect of profile elevation on the relationship between interest differentiation and vocational identity. British Journal of Guidance & Counselling, 39, 149–160. doi:10.1080/03069885.2010.547054
57. Ion, A., Nye, C. D., & Iliescu, D. (2019). Age and gender differences in the variability of vocational interests. Journal of Career Assessment, 27(1), 97–113. doi:10.1177/1069072717748646
58. Ishitani, T. T. (2010). Exploring the effects of congruence and Holland's personality codes on job satisfaction: An application of hierarchical linear modeling techniques. Journal of Vocational Behavior, 76, 16–24. doi:10.1016/j.jvb.2009.06.014
59. Jo, H., Ra, Y., Lee, J., & Kim, W. H. (2016). Impact of dysfunctional career thoughts on career decision self‐efficacy and vocational identity. The Career Development Quarterly, 64, 333–344. doi:10.1002/cdq.12069
60. Kantamneni, N. (2014). Vocational interest structures for Asian Americans, Middle‐Eastern Americans and Native Americans on the 2005 Strong Interest Inventory. Journal of Vocational Behavior, 84, 133–141. doi:10.1016/j.jvb.2013.11.003
61. Kantamneni, N., & Fouad, N. (2011). Structure of vocational interests for diverse groups on the 2005 Strong Interest Inventory. Journal of Vocational Behavior, 78, 193–201. doi:10.1016/j.jvb.2010.06.003
62. Krieshok, T. S., Hansen, R. N., Johnston, J. A., & Wong, S. C. (2002). Missouri occupational card sort manual. Columbia, MO: University of Missouri.
63. Kristof‐Brown, A. L., Zimmerman, R. D., & Johnson, E. C. (2005). Consequences of individual's fit at work: A meta‐analysis of person‐job, person‐organization, person‐group, and person‐supervisor fit. Personnel Psychology, 58, 281–342. doi:10.1111/j.1744‐6570.2005.00672.x
64. Larson, L. M., Rottinghaus, P. J., & Borgen, F. H. (2002). Meta‐analyses of Big Six interests and Big Five personality factors. Journal of Vocational Behavior, 61, 217–239. doi:10.1006/jvbe.2001.1854
65. Lent, R. W., Tracey, T. J. G., Brown, S. D., Soresi, S., & Nota, L. (2006). Development of interests and competency beliefs in Italian adolescents: An exploration of circumplex structure and bidirectional relationships. Journal of Counseling Psychology, 53, 181–191. doi:10.1037/0022‐0167.53.2.181
66. Leong, F., Austin, J., Sekaran, U., & Komarraju, M. (1998). An evaluation of the cross‐cultural validity of Holland's theory: Career choices by workers in India. Journal of Vocational Behavior, 52, 441–455. doi:10.1006/jvbe.1997.1637
67. Leung, S. A. (1998). Vocational identity and career choice congruence of gifted and talented high school students. Counselling Psychology Quarterly, 11, 325–335. doi:10.1080/09515079808254064
68. Leung, S. A., Conoley, C. W., Scheel, M. J., & Sonnenberg, R. T. (1992). An examination of the relation between vocational identity, consistency, and differentiation. Journal of Vocational Behavior, 40, 95–107. doi:10.1016/0001‐8791(92)90049‐6
69. Leuty, M. E., & Hansen, J.‐I. C. (2013). Building evidence of validity: The relation between work values, interests, personality, and personal values. Journal of Career Assessment, 21, 175–189. doi:10.1177/1069072712466714
70. Lewis, P., & Rivkin, D. (1999). Development of the O*Net interest profiler. Raleigh: NC: National Center for O*NET development.
71. Liu, S., Huang, J. L., & Wang, M. (2014). Effectiveness of job search interventions: A meta‐analytic review. Psychological Bulletin, 140, 1009–1041. doi:10.1037/a0035923
72. Low, K. S. D., Yoon, M., Roberts, B. W., & Rounds, J. (2005). The stability of vocational interests from early adolescence to middle adulthood: A quantitative review of longitudinal studies. Psychological Bulletin, 131, 713–737. doi:10.1037/0033‐2909.131.5.713
73. Maurer, T. J., & Tarulli, B. A. (1997). Managerial work, job analysis, and Holland's RIASEC vocational environment dimensions. Journal of Vocational Behavior, 50, 365–381. doi:10.1006/jvbe.1996.1549
74. McCrae, R. R., & Costa, P. T. (1987). Validation of the five‐factor model of personality across instruments and observers. Journal of Personality and Social Psychology, 52(1), 81–90. https://doi.org/10.1037/0022-3514.52.1.81
75. Messer, M. A., Greene, J. A., Kovacs, A. M., & Holland, J. L. (2013). The leisure activities finder. Lutz, FL: PAR.
76. Messer, M. A., Holland, J. L., & PAR Staff. (2013). Educational opportunities finder. Lutz, FL: PAR.
77. Moore, M. A., Neimeyer, G. J., & Marmarosh, C. (1992). Effects of informational valence and occupational favorability on vocational differentiation: A test of the disconfirmation hypothesis. Journal of Counseling Psychology, 39, 335–341. doi:10.1037/0022‐0167.39.3.335
78. Morgan, B., & de Bruin, G. P. (2018). Structural validity of Holland's circumplex model of vocational personality types in Africa. Journal of Career Assessment, 26(2), 275–290. doi:10.1177/1069072717692747
79. Mount, M. K., Barrick, M. R., Scullen, S. M., & Rounds, J. (2005). Higher‐order dimensions of the big five personality traits and the big six vocational interest types. Personnel Psychology, 58, 447–478. doi:10.1111/j.1744‐6570.2005.00468.x
80. Nauta, M. M. (2010). The development, evolution, and status of Holland's theory of vocational personalities: Reflections and future directions for counseling psychology. Journal of Counseling Psychology, 57, 11–22. doi:10.1111/j.1464‐0597.2008.00375.x
81. Negru‐Subtirica, O., Pop, E. I., & Crocetti, E. (2015). Developmental trajectories and reciprocal associations between career adaptability and vocational identity: A three‐wave longitudinal study with adolescents. Journal of Vocational Behavior, 88, 131–142. https://doi.org/10.1016/j.jvb.2015.03.004
82. Nye, C. D., Perlus, J. G., & Rounds, J. (2018). Do ornithologists flock together? Examining the homogeneity of interests in occupations. Journal of Vocational Behavior, 107, 195–208. doi:10.1016/j.jvb.2018.04.004
83. Nye, C. D., Prasad, J., Bradburn, J., & Elizondo, F. (2018). Improving the operationalization of interest congruence using polynomial regression. Journal of Vocational Behavior, 104, 154–169. https://doi.org/10.1016/j.jvb.2017.10.012
84. Nye, C. D., Su, R., Rounds, J., & Drasgow, F. (2012). Vocational interests and performance: A quantitative summary of over 60 years of research. Perspectives on Psychological Science, 7(4), 384–403. doi:10.1177/1745691612449021
85. Nye, C. D., Su, R., Rounds, J., & Drasgow, F. (2017). Interest congruence and performance: Revisiting recent meta‐analytic findings. Journal of Vocational Behavior, 98, 138–151. https://doi.org/10.1016/j.jvb.2016.11.002
86. Oleski, D., & Subich, L. M. (1996). Congruence and career change in employed adults. Journal of Vocational Behavior, 49, 221–229. doi:10.1006/jvbe.1996.0041
87. Perdue, S. V., Reardon, R. C., & Peterson, G. W. (2007). Person‐environment congruence, self‐efficacy, and environmental identity in relation to job satisfaction: A career decision theory perspective. Journal of Employment Counseling, 44, 29–39.
88. Phan, W. M. J., & Rounds, J. (2018). Examining the duality of Holland's RIASEC types: Implications for measurement and congruence. Journal of Vocational Behavior, 106, 22–36. doi:10.1016/j.jvb.2017.11.011
89. Porfeli, E. J., Lee, B., Vondracek, F. W., & Weigold, I. K. (2011). A multi‐dimensional measure of vocational identity status. Journal of Adolescence, 34, 853–871. doi:10.1016/j.adolescence.2011.02.001
90. Porfeli, E. J., & Savickas, M. L. (2012). Career Adapt‐Abilities Scale‐USA Form: Psychometric properties and relation to vocational identity. Journal of Vocational Behavior, 80, 748–753. doi:10.1016/j.jvb.2012.01.009
91. Prediger, D. J. (1982). Dimensions underlying Holland's hexagon: Missing link between interests and occupations? Journal of Vocational Behavior, 48, 59–67. doi:10.1016/0001‐8791(82)90036‐7
92. Rachman, D., Amernic, J., & Aranya, N. (1981). A factor‐analytic study of the construct validity of Holland's Self‐Directed Search test. Educational and Psychological Measurement, 41, 425–437. doi:10.1177/001316448104100221
93. Rounds, J., Smith, T., Hubert, L., Lewis, P., & Rivkin, D. (1999). Development of occupational interest profiles for O*Net. Raleigh, NC: National Center for O*NET Development.
94. Rounds, J., & Tracey, T. J. G. (1993). Prediger's dimensional representation of Holland's RIASEC circumplex. Journal of Applied Psychology, 78, 875–890. doi:10.1037/0021‐9010.78.6.875
95. Rounds, J. B., & Tracey, T. J. G. (1996). Cross‐cultural structural equivalence of RIASEC models and measures. Journal of Counseling Psychology, 43, 310–329. doi:10.1037/0022‐0167.43.3.310
96. Ryan, J. M., Tracey, T. J. G., & Rounds, J. (1996). Generalizability of Holland's structure of vocational interests across ethnicity, gender, and socioeconomic status. Journal of Counseling Psychology, 43, 330–337. doi:10.1037/0022‐0167.43.3.330
97. Spokane, A. R. (1985). A review of research on person‐environment congruence in Holland's theory of careers [Monograph]. Journal of Vocational Behavior, 26, 306–343. doi:10.1016/0001‐8791%2885%2990009‐0
98. Spokane, A. R., Meir, E. I., & Catalano, M. (2000). Person‐environment congruence and Holland's theory: A review and reconsideration. Journal of Vocational Behavior, 57, 137–187. doi:10.1006/jvbe.2000.1771
99. Strahan, R. F. (1987). Measures of consistency for Holland‐type codes. Journal of Vocational Behavior, 31, 37–44. doi:10.1016/0001‐8791(87)90033‐9
100. Su, R., Rounds, J., & Armstrong, P. I. (2009). Men and things, women and people: A meta‐analysis of sex differences in interests. Psychological Bulletin, 135, 859–884. doi:10.1037/a0017364
101. Sung, Y.‐T., Cheng, Y.‐W., & Wu, J.‐S. (2016). Constructing a situation‐based career interest assessment for junior high school students and examining their interest structure. Journal of Career Assessment, 24, 347–365. doi:10.1177/1069072715580419
102. Swaney, K. B. (1995). Technical manual: Revised unisex edition of the ACT Interest Inventory (UNIACT). Iowa City, IA: ACT.
103. Swanson, J. L. (1999). Stability and change in vocational interests. In M. L. Savickas & A. R. Spokane (Eds.), Vocational interests: Meaning, measurement, and counseling use (pp. 135–158). Palo Alto, CA: Davies‐Black.
104. Tracey, T. J. G. (2008). Adherence to RIASEC structure as a key career decision construct. Journal of Counseling Psychology, 55, 146–157. doi:10.1037/0022‐0167.55.2.146
105. Tracey, T. J. G., & Robbins, S. B. (2006). The interest‐major congruence and college success relation: A longitudinal study. Journal of Vocational Behavior, 69, 64–89. doi:10.1016/j.jvb.2005.11.003
106. Tracey, T. J. G., & Rounds, J. B. (1993). Evaluating Holland's and Gati's vocational interest models: A structural meta‐analysis. Psychological Bulletin, 113, 229–246. doi:10.1037/0033‐2909.113.2.229
107. Tracey, T. J. G., Wille, B., Durr, M. R., II, & De Fruyt, F. (2014). An enhanced examination of Holland's consistency and differentiation hypotheses. Journal of Vocational Behavior, 84, 237–247. doi:10.1016/j.jvb.2014.01.008
108. Tranberg, M., Slane, S., & Ekeberg, S. E. (1993). The relation between interest congruence and satisfaction: A metaanalysis. Journal of Vocational Behavior, 42, 253–264. doi:10.1006/jvbe.1993.1018
109. Tsabari, O., Tziner, A., & Meir, E. I. (2005). Updated meta‐analysis on the relationship between congruence and satisfaction. Journal of Career Assessment, 13, 216–232. doi:10.1177/1069072704273165
110. U.S. Department of Defense. (2005). ASVAB career exploration program counselor manual (DD form 1304‐SCM). Seaside, CA: Defense Manpower Data Center.
111. Van Iddekinge, C. H., Roth, P. L., Putka, D. J., & Lanivich, S. E. (2011). Are you interested? A meta‐analysis of relations between vocational interests and employee performance and turnover. Journal of Applied Psychology, 96(6), 1167–1194. doi: 10.1037/a0024343
112. Wille, B., Tracey, T. J. G., Feys, M., & De Fruyt, F. (2014). A longitudinal and multi‐method examination of interest–occupation congruence within and across time. Journal of Vocational Behavior, 84, 59–73. doi:10.1016/j.jvb.2013.12.001
113. Williams, C. M. (1972). Occupational choice of male graduate students as related to values and personality: A test of Holland's theory. Journal of Vocational Behavior, 2, 39–46. doi:10.1016/0001‐8791(72)90005‐X
114. Xu, H., & Tracey, T. J. G. (2016). Stability and change in interests: A longitudinal examination of grades 7 through college. Journal of Vocational Behavior, 93, 129–138. doi:10.1016/j.jvb.2016.02.002
115. Yang, W., Stokes, G. S., & Hui, C. H. (2005). Cross‐cultural validation of Holland's interest structure in Chinese population. Journal of Vocational Behavior, 67, 379–396. doi:10.1016/j.jvb.2004.08.003
116. Yang, Y., Morris, M. L., & Protolipac, D. S. (2018). Simplified Chinese version of the Strong Interest Inventory: Structure and psychometric properties. Journal of Vocational Behavior, 108, 214–226. doi:10.1016/j.jvb.2018.08.009
117. Young, G., Tokar, D. M., & Subich, L. M. (1998). Congruence revisited: Do 11 indices differentially predict job satisfaction and is the relation moderated by person and situation variables? Journal of Vocational Behavior, 52, 208–233. doi:10.1006/jvbe.1997.1587