First and foremost, we would like to thank our x-teams—those featured in the book and those that we’ve studied and worked with over the years. You have been the catalyst for our theory, and you have brought the theory to life in your projects. You have inspired us with your work, spirit, enthusiasm, and great ideas and innovations. Thank you for taking us along on the ride. We would also like to thank the organizations that have let us come in to observe, work, and experiment.

We owe a great intellectual debt to David Caldwell, who helped to build the theoretical foundations of this book. Thanks also to David for being a great friend, scholar, and coauthor.

We want to thank our academic mentors and colleagues who have helped us get to where we are today. From Deborah, thanks to the late David Nadler, who provided access to nursing teams and sales teams, and who offered guidance and then let me learn on my own. David also showed me the benefits of linking practice and theory. Thanks to the late Richard Hackman for helping us push the theoretical envelope and for the wisdom. Thanks to Michael Tushman for mentoring and friendship over the long term. Thanks to Sue Ashford and Jim Walsh for helping us through those early academic years. At MIT, thanks to the folks in Executive Education for creating the architecture for x-teams and to Andrew Lo for opening doors and believing. Thanks to Lotte Bailyn and Wanda Orlikowski for advice and for being there when needed.

For Henrik, Deborah is not only a coauthor—long before the writing of this book, she was also the best academic adviser any doctoral student could have. Many thanks go to Amy Edmondson, an extraordinary mentor during the early days who has been an incomparable source of inspiration and support ever since. Thanks to Örjan Sölvell and the late Gunnar Hedlund for encouraging me to take a closer look at an academic career and to Julian Birkinshaw for motivating me to pursue it seriously. Thanks to Eleanor Westney for generously opening the doors to MIT all those years ago and to all the extraordinary people found inside those doors. My fellow doctoral students from MIT form a community of scholars and friends that I am grateful to be a member of. Finally, thanks to the students, staff, alumni, and colleagues at INSEAD who keep feeding my curiosity and disciplining my thinking.

We thank the MIT Sloan School and INSEAD for providing the environment, resources, and infrastructure needed for our work. Thanks to the Harvard Business Review Press staff, especially Jeff Kehoe, for advising and shepherding us from manuscript to finished product. And big thanks to our editor Lynn Selhat, who helped us move from confusion to clarity as we pulled together this book’s second edition.

Finally, thanks to our friends and families for encouraging us despite all the times we weren’t available and weren’t in the best of moods. We dedicate the book to our children—you make us happy and proud.