Michael Kremer is Gates Professor of Developing Societies at Harvard University, Senior Fellow at the Brookings Institution, and NonResident Fellow at the Center for Global Development. He founded and was the first executive director of WorldTeach, a nonprofit organization that places two hundred volunteer teachers annually in developing countries (1986-1989). He previously served as a teacher in Kenya. Rachel Glennerster is Director of the Poverty Action Lab at the Massachusetts Institute of Technology, a center devoted to evaluating the effectiveness of anti-poverty programs. She has worked