Many have contributed to my research on psychological safety in the quarter century since I stumbled into the phenomenon by accident. First, there are the managers, nurses, physicians, engineers, frontline associates, CEOs, and other employees in the many organizations that opened their doors to this university researcher. I am grateful for their willingness to be interviewed and studied; their generous contributions of time and insight made the work summarized in this book possible. I also thank the Division of Research at Harvard Business School for generous financial support that funded this research. I have been gratified in recent years by the dozens of both new and experienced researchers who have picked up on the concept of psychological safety to include it in their studies, adding valuable discoveries to the growing literature on this topic; their diverse, creative, rigorous research lends immense support to the argument that psychological safety matters for excellence in organizations around the world.

I am especially grateful to Jeanenne Ray at Wiley for her confidence in my work and for her patience as I sailed right past our original deadline. Patrick Healy provided invaluable research assistance that contributed to the quality and depth of the evidence I can offer to readers. In particular, he conducted literature reviews of both academic and practitioner writings on psychological safety, painstakingly reading and making notes on hundreds of articles. He identified numerous case studies that helped bring these ideas to life. His suggestions, edits, and enthusiasm for the topic truly contributed to making this a better book. Pat also took on the thankless tasks of managing references, permissions, and other endless details that go into a project like this with skill, precision, and remarkable good cheer. I received insightful feedback at different points in the writing process from three brilliant friends – Roger Martin, Susan Salter Reynolds, and Paul Verdin – that made crucial improvements possible. Sara Nicholson provided essential help with proofing, with her usual level of extraordinary competence.

Of the many people who contributed to getting this book into its final shape, Karen Propp is by far the most important. I am deeply grateful to been able to work with her on this project. Without her perceptive questions, insights, ideas, stories, and well-honed skills as a writer and editor, this book would never have been finished. I think it's fair to say that Karen, Pat, and I had fun teaming up – identifying the cases and ideas that made it into the final draft, along with those that didn't. I hope you will find our choices to have been good ones for capturing the richness and diversity of the settings in which psychological safety matters for learning and fulfillment at work.

Finally, my husband, George Daley, put up with me as I put more and more time into working and writing. His love and confidence sustained me and made it possible for me to devote every spare moment to getting this done. He was there every step of the way for the past 25 years, never losing faith in me or in my work. While I spend my days studying leaders who make a difference in the world, George is one – having taken on the challenge of leading a major organization two years ago. Humble enough to claim my ideas have helped him succeed, George has thus given me even greater confidence that they may help others as well. This book is dedicated to him.