There's a lot out there on polyamory, as well as the skills—such as communication and cultivating healthy self-esteem—that are useful in creating happy poly relationships. With the list below, we've tried to present a few of the standouts in each category.
Relationships
The Dance of Intimacy: A Woman's Guide to Courageous Acts of Change in Key Relationships, Harriet Lerner (Harper Perennial, 1989). A classic book, geared at women but useful for everyone, on maintaining clear boundaries and a strong self while building intimacy in relationships. Harriet Lerner also maintains an excellent (though monogamy-focused) blog on the Psychology Today website.
Daring Greatly: How the Courage to Be Vulnerable Transforms the Way We Live, Love, Parent, and Lead, Brené Brown (Penguin, 2012). About expressing courage in all our relationships and throughout our lives by daring to be our most authentic selves.
Emotional Blackmail: When the People in Your Life Use Fear, Obligation, and Guilt to Manipulate You, Susan Forward and Donna Frazier (William Morrow, 1998). A primer on recognizing and dealing with emotional manipulation and blackmail in romantic relationships.
Self
The Gifts of Imperfection: Let Go of Who You Think You're Supposed to Be and Embrace Who You Are, Brené Brown (Hazelden, 2010). A small but life-changing, evidence-based book on confronting insecurity, believing in our own worthiness and living what Brown calls "wholehearted" lives. Brown also writes a blog at brenebrown.com.
The How of Happiness: A New Approach to Getting the Life You Want, Sonja Lyubomirsky (Penguin, 2007). Another research-based book that delves into the factors in personal happiness that are within our control.
Communication and conflict
The Dance of Connection: How to Talk to Someone When You're Mad, Hurt, Scared, Frustrated, Insulted, Betrayed, or Desperate, Harriet Lerner (HarperCollins, 2009). Excellent techniques for high-stakes communication in any kind of relationship and emotionally charged situations.
Nonviolent Communication: A Language of Life: Life-Changing Tools for Healthy Relationships, Marshall Rosenberg and Arun Gandhi (Puddledancer Press, 2008). A guidebook for clear, compassionate communication that teaches the foundations of authentic communication without bullying.
The Joy of Conflict Resolution: Transforming Victims, Villains and Heroes in the Workplace and at Home, Gary Harper (New Society Publishers, 2009, available direct from newsociety.com). On the "drama triangle" in conflict and how to find a path out of it through curiosity and compassion.
Messages: The Communication Skills Book, Matthew McKay, Martha Davis and Patrick Fanning (New Harbinger Publications, 2009). A workbook containing practical exercises for improving personal communication skills in personal and professional life.
Sex
The best, most current information on STI prevention and testing can be found at the websites of the U.S. Centers for Disease Control and Prevention (cdc.gov) and Planned Parenthood (plannedparenthood.org).
The Ethical Slut: A Practical Guide to Polyamory, Open Relationships and Other Adventures, Dossie Easton and Janet W. Hardy (Greenery Press, 2nd ed., 2011). The landmark book on non-monogamy, first published in 1997.
A Tired Woman's Guide to Passionate Sex: Reclaim Your Desire and Reignite Your Relationship, Laurie B. Mintz (Adams Media, 2009). A book aimed at heterosexual women with the goal of rekindling desire in long-term relationships, with success that has been supported by peer-reviewed research.
Polyamory
Redefining Our Relationships: Guidelines for Responsible Open Relationships, Wendy-O Matik (Defiant Times Press, 2002). A tiny manifesto on abandoning the relationship escalator and creating intentional, ethically non-monogamous relationships.
The Polyamorists Next Door: Inside Multiple-Partner Relationships and Families, Elisabeth Sheff (Rowman & Littlefield Publishers, 2013). An in-depth, inside view of polyamorous families based on over a decade of research.
The Polyamory on Purpose Guide to Poly and Pregnancy, Jessica Burde (CreateSpace, 2013). A complete guide to pregnancy in poly relationships, covering topics including planned pregnancy, unintended pregnancy, custody and child care.
Blogs and websites
More Than Two, morethantwo.com. Franklin's own website, maintained since 1997, with a wealth of information on managing poly relationships. He and Eve also maintain a blog at morethantwo.com/blog.
Solopoly, solopoly.net. An excellent blog from a solo poly perspective, covering everything from the politics to the practicalities of solo polyamory.
The Polyamorous Misanthrope, polyamorousmisanthrope.com. A long-running blog that's a gold mine of supremely practical poly advice, all written with a good dose of humor.
The Radical Poly Agenda, radicalpoly.wordpress.com. A blog that takes on the political and ideological implications of polyamory from a feminist, anarchic perspective.
Sex Geek, sexgeek.wordpress.com. Andrea Zanin's blog on polyamory, sex positivity, kink, and all things sexy and geeky. Pragmatic poly advice that goes beyond the couple-focused, heterosexual, monogamy-plus model.
Polyamory in the News, polyinthemedia.blogspot.ca. A site that reviews global media coverage of polyamory and also contains comprehensive lists of worldwide poly events, poly groups and poly books.
Polyamory Weekly, polyweekly.com. A weekly, down-to-Earth podcast by Cunning Minx, covering poly issues with a good dose of compassion and humor.
Memoir
The Game Changer: A Memoir of Disruptive Love, Franklin Veaux (Thorntree Press, 2015). Franklin’s memoir, with the complete stories of his relationships with Celeste, Ruby, Bella and Amber, and how his hierarchical mindset shifted to one that honored his partners’ agency.
Open: Love, Sex and Life in an Open Marriage, Jenny Block (Seal Press, 2009). A personal memoir of suburban polyamory that narrates Block's exploration beyond her monogamous relationship.
The Husband Swap: A True Story of Unconventional Love, Louisa Leontiades (second edition, Thorntree Press, 2015). An emotionally raw and deeply vulnerable memoir of Leontiades's entry into polyamory when she and her husband began a cross-coupled quad. Likely to resonate with many couples who are in the early stages of opening their relationship.