Responsible Transparency: The Millennium Challenge Corporation’s Experience with Microdata Protection and Dissemination Stephanie Burch, Heather Hanson, Jack Molyneaux, Jennifer Sturdy Abstract: The Millennium Challenge Corporation (MCC) is a U.S. foreign development agency that supports poverty reduction through economic growth in better governed poor countries. The agency uses a data-based approach to select country partners, and design, monitor, and evaluate programs, which has resulted in a wealth of data resources in its first 10 years. With a commitment to transparency built into the MCC model as a means for accountability and learning, it has the incentives in place and has allocated resources to begin addressing the legal, ethical, and practical issues related to the public release of one particular data type - microdata. In 2012, MCC identified a set objectives for public release of its evaluation-related microdata: enabling replicability of results, maximizing data usability, and minimizing risk to the individuals, households, firms, and communities who provided the data. These different objectives are sometimes in competition, and in order to manage this inherent tension, MCC implemented a series of actions, including establishing: (i) a microdata dissemination mechanism, (ii) data protection principles, (iii) an internal Disclosure Review Board, (iv) procedures for restricted-access to certain data, and (v) staffing and resources to implement the data protection principles. The paper discusses this experience and concludes with a set of lessons learned as MCC works with its partners to balance the release of its evaluation-related microdata with the protection of survey respondents’ privacy. Keywords: transparency; open data; results data; microdata; evaluations; anonymization; privacy; data protection