This book has an entire chapter on mass collaboration, but it is itself a mass collaboration. Quite simply this book would not exist were it not for the generous support of many wonderful people and organizations. For that, I am extremely grateful.

Many people provided feedback about one or more of these chapters or had extended conversations with me about the book. For this valuable feedback, I am grateful to Hunt Allcott, David Baker, Solon Baracas, Chico Bastos, Ken Benoit, Clark Bernier, Michael Bernstein, Megan Blanchard, Josh Blumenstock, Tom Boellstorff, Robert Bond, Moira Burke, Yo-Yo Chen, Dalton Conley, Shelley Correll, Jennifer Doleac, Don Dillman, Ethan Fast, Nick Feamster, Cybelle Fox, Maggie Frye, Alan Gerber, Sharad Goel, Don Green, Eitan Hersh, Jake Hofman, Greg Huber, Joanna Huey, Patrick Ishizuka, Ben Jones, Steve Kelling, Dawn Koffman, Sasha Killewald, Harrissa Lamothe, Andrés Lajous, David Lee, Amy Lerman, Meagan Levinson, Andrew Ledford, Kevin Lewis, Dai Li, Karen Levy, Ian Lundberg, Xiao Ma, Andrew Mao, John Levi Martin, Judie Miller, Arvind Naranyanan, Gina Neff, Cathy O’Neil, Nicole Pangborn, Ryan Parsons, Devah Pager, Arnout van de Rijt, David Rothschild, Bill Salganik, Laura Salganik, Christian Sandvig, Mattias Smångs, Sid Suri, Naomi Sugie, Brandon Stewart, Michael Szell, Sean Taylor, Florencia Torche, Rajan Vaish, Janet Vertesi, Taylor Winfield, Han Zhang, and Simone Zhang. I would also like to thank three anonymous reviewers who provided helpful feedback.

I also received wonderful feedback on a draft manuscript from the participants in the Open Review process: akustov, benzevenbergen, bp3, cailinh, cc23, cfelton, chase171, danivos, DBLarremore, differentgranite, dmerson, dmf, efosse, fasiha, hrthomas, huntr, istewart, janetxu, jboy, jeremycohen, jeschonnek.1, jtorous, judell, jugander, kerrymcc, leohavemann, LMZ, MMisra, Nick_Adams, nicolemarwell, nir, person, pkrafft, raminasotoudeh, rchew, rkharkar, sculliwag, sjk, Stephen_L_Morgan, sweissman, toz, and vnemana. I would also like to thank the Sloan Foundation and Josh Greenberg for supporting the Open Review Toolkit. If you’d like to put your own book through Open Review, please visit

I would also like to thank the organizers and participants at the following events where I had a chance to talk about the book: Cornell Tech Connective Media Seminar; Princeton Center for the Study of Democratic Politics Seminar; Stanford HCI Colloquium; Berkeley Sociology Colloquium; Russell Sage Foundation Working Group on Computational Social Science; Princeton DeCamp Bioethics Seminar; Columbia Quantitative Methods in the Social Sciences Visiting Speaker Series; Princeton Center for Information Technology Policy Technology and Society Reading Group; Simons Institute for the Theory of Computing Workshop on New Directions in Computational Social Science & Data Science; Data and Society Research Institute Workshop; University of Chicago, Sociology Colloquium; International Conference on Computational Social Science; Data Science Summer School at Microsoft Research; Society for Industrial and Applied Mathematics (SIAM) Annual Meeting; Indiana University, the Karl F. Schuessler Lecture in the Methodologies of Social Research; the Oxford Internet Institute; MIT, Sloan School of Management; AT&T Research’ Renaissance Technologies; University of Washington, Data Science Seminar; SocInfo 2016; Microsoft Research, Redmond; Johns Hopkins, Population Research Center; New York City Data Science Seminar; and ICWSM 2017.

Many students over the years have shaped the ideas in this book. I would especially like to thank the students in Sociology 503 (Techniques and Methods of Social Science) in Spring 2016 for reading an early version of the manuscript, and the students in Sociology 596 (Computational Social Science) in Fall 2017 for pilot testing a complete draft of this manuscript in a classroom setting.

Another source of wonderful feedback was my book manuscript workshop that was organized by Princeton’s Center for the Study of Democratic Politics. I would like to thank Marcus Prior and Michele Epstein for supporting the workshop. And I would like to thank all of the participants who took time from their busy lives to help me improve the book: Elizabeth Bruch, Paul DiMaggio, Filiz Garip, Meagan Levinson, Karen Levy, Mor Naaman, Sean Taylor, Markus Prior, Jess Metcalf, Brandon Stewart, Duncan Watts, and Han Zhang. It really was a wonderful day—one of the most exciting and rewarding of my entire career—and I hope that I’ve been able to channel some of wisdom from that room into the final manuscript.

A few other people deserve special thanks. Duncan Watts was my dissertation adviser, and it was my dissertation that got me excited about social research in the digital age; without the experience that I had in graduate school this book would not exist. Paul DiMaggio was the first person to encourage me to write this book. It all happened one afternoon while we were both waiting for the coffee machine in Wallace Hall, and I still remember that up until that time, the idea of writing a book had never even crossed my mind. I am deeply grateful to him for convincing me that I had something to say. I’d also like to thank Karen Levy for reading nearly all of the chapters in their earliest and messiest forms; she helped me see the big picture when I was stuck in the weeds. I’d like to thank Arvind Narayanan for helping me focus and refine the arguments in the book over many wonderful lunches. Brandon Stewart was always happy to chat or look at chapters, and his insights and encouragement kept me moving forward, even when I was starting to drift sideways. And, finally, I would like to thank Marissa King for helping me come up with the title to this book one sunny afternoon in New Haven.

While writing this book, I benefited from the support of three amazing institutions: Princeton University, Microsoft Research, and Cornell Tech. First, at Princeton University, I’m grateful to my colleagues and students in the Department of Sociology for creating and maintaining a warm and supportive culture. I would also like to thank the Center for Information Technology Policy for providing me with a wonderful intellectual second home where I could learn more about how computer scientists see the world. Portions of this book were written while I was on sabbatical from Princeton, and during those leaves I was lucky enough to spend time in two fantastic intellectual communities. First, I would like to thank Microsoft Research New York City for being my home in 2013-14. Jennifer Chayes, David Pennock, and the entire computational social science group were wonderful hosts and colleagues. Second, I would like to thank Cornell Tech for being my home in 2015-16. Dan Huttenlocher, Mor Naaman, and everyone in the Social Technologies Lab helped make Cornell Tech the ideal environment for me to finish this book. In many ways, this book is about combining ideas from data science and social science, and Microsoft Research and Cornell Tech are models of this kind of intellectual cross-pollination.

While writing this book, I had excellent research assistance. I am grateful to Han Zhang, especially for his help making the graphs in this book. I am grateful to Yo-Yo Chen, especially for her help drafting the activities in this book. Finally, I am grateful to Judie Miller and Kristen Matlofsky for assistance of all kinds.

The web version of this book was created by Luke Baker, Paul Yuen, and Alan Ritari of the Agathon Group. Working with them on this project was a pleasure, as always. I would especially like to thank Luke for also developing the build process for this book and helping me navigate the dark corners of Git, pandoc, and Make.

I would like to thank the contributors to the following projects that we used: Git, pandoc, pandoc-crossref, pandoc-citeproc, pandoc-citeproc-preamble, Hypothesis, Middleman, Bootstrap, Nokogiri, GNU Make, Vagrant, Ansible, LaTeX, and Zotero. All graphs in this book were created in R (R Core Team 2016), and used the following packages: ggplot2 (Wickham 2009), dplyr (Hadley Wickham and Francois 2015), reshape2 (Wickham 2007), stringr (Hadley Wickham 2015), car (Fox and Weisberg 2011), cowplot (Wilke 2016), png (Urbanek 2013), grid (R Core Team 2016), and ggrepel (Slowikowski 2016). I would also like to thank Kieran Healy for his blog post that got me started with pandoc.

I would like to thank Arnout van de Rijt and David Rothschild for providing data used to recreate some of the graphs from their papers and Josh Blumenstock and Raj Chetty for making public replication files available.

At Princeton University Press, I would like to thank Eric Schwartz who believed in this project at the beginning, and Meagan Levinson who helped make it a reality. Meagan was the best editor that a writer could have; she was always there to support this project, in good times and in bad times. I’m particuarly grateful for how her support has evolved as the project has changed. Al Bertrand did a great job stepping in during Meagan’s leave, and Samantha Nader and Kathleen Cioffi helped turn this manuscript into a real book.

Finally, I would like to thank my friends and family. You have been supportive of this project in so many ways, often in ways that you did not even know. I would especially like to thank my parents, Laura and Bill, and my parents-in-law, Jim and Cheryl, for their understanding while this project went on and on and on. I would also like to thank my kids. Eli and Theo, you have asked me so many times when my book will finally be finished. Well, it is finally finished. And, most importantly, I want to thank my wife Amanda. I’m sure that you too have wondered when this book would finally be finished, but you never showed it. Over the years that I’ve worked on this book, I’ve been absent too much, both physically and mentally. I am so appreciative of your never-ending support and love.