This book is possible because of the superb leadership of mayors of cities in numerous countries of the world, and because they freely share their ideas and concepts. In turn, the mayors and the city governments they lead would not have been able to succeed without the support, advice, and excellence of the public servants of those cities. In the same way, I am indebted to the University of Waterloo, Faculty of Environmental Studies, for its support; to my publisher, University of Toronto Press, and my editor, Jodi Lewchuk, whose advice and guidance was invaluable; to her colleagues Catherine Plear and Janice Evans, whose talented editing brought this book to completion; and particularly to Heather McDiarmid, my researcher, who, in addition to excellent research, wrote the first drafts of significant parts of several chapters and helped to turn the clear narrative I knew into a substantive book.