Democratic nations have long struggled to set the proper balance between individual freedom and government control. The rise of digital communications networks, market integration, and international terrorism has transformed many national civil liberties issues into important international debates. The European Union was among the first jurisdictions to manage these new transnational civil liberties with the adoption of a data privacy directive in 1995. The directive substantially expanded privacy protection within Europe and had far-reaching consequences internationally. While international relations scholars have paid considerable attention to the global ramifications of these rules, research has not yet explained the origins of the European data privacy directive. Given the resistance from the European Commission, powerful member states, and industry to their introduction, the adoption of supranational rules presents a striking empirical puzzle. This article conducts a structured evaluation of conventional approaches to European integration—liberal intergovernmentalism and neofunctionalism—against the historical record and uncovers an alternative driver: transgovernmental actors. These transgovernmental actors are endowed with power resources—expertise, delegated political authority, and network ties—that they employ to promote their regional policy goals. This article uses the historical narrative of the data privacy directive to explain the origins of a critical piece of international civil liberties legislation and to advance a theoretical discussion about the role of transgovernmental actors as policy entrepreneurs within the multilevel structure of the European Union.An earlier version of this article was presented at the 99th Annual Meeting of the American Political Science Association, Philadelphia, 28–31 August 2003. I would like to thank David Bach, Tim Büthe, Burkard Eberlein, Pat Egan, Henry Farrell, Orfeo Fioretos, Jane Gingrich, Virginia Haufler, Jonah Levy, Kate McNamara, Sophie Meunier, Craig Pollack, Mark Pollack, Elliot Posner, Kathryn Sikkink, Wolfgang Streeck, Steve Weber, Nick Ziegler, and John Zysman for extensive comments on earlier drafts of the manuscript. Funding for this research was provided by the Berkeley Roundtable on the International Economy and the Max Planck Institute for the Study of Societies, Cologne, Germany.