Leonid Hurwicz is Regents' Professor of Economics Emeritus at the University of Minnesota. Internationally renowned for his pioneering research on economic theory, particularly in the areas of mechanism and institutional design and mathematical economics, he received the national Medal of Science in 1990. A member of the National Academy of Sciences and the American Academy of Arts and Sciences, Professor Hurwicz is a former President and Fellow of the Econometric Society. The recipient of six honorary doctorates, he serves on the editorial board of several journals and coedited and contributed to two collections for Cambridge University Press, Studies in Resource Allocation Processes (1978, with Kenneth Arrow) and Social Goals and Social Organization (1987, with David Schmeidler and Hugo Sonnenschein).His recent publications include papers in Economic Theory (2003, with Thomas Marschak), Review of Economic Design (2001, with Stanley Reiter), and Advances in Mathematical Economics (2003, with Marcel K. Richter). Stanley Reiter is Morrison Professor of Economics and Mathematics in the Weinburg College of Arts and Sciences and Morrison Professor of Managerial Economics and Decision Sciences in the Kellogg School of Management, Northwestern University, where he directs the Center for Mathematical Studies in Economics and Management Science. He previously served as Krannert Professor of Economic and Mathematics at Purdue University. A Fellow of the American Academy for the Advancement of Science, the American Academy of Arts and Sciences, the Guggenheim Foundation, and the Econometric Society, Professor Reiter is coauthor (with Kenneth R. Mount) of Computation and Complexity in Economic Behavior and Organization (Cambridge University Press, 2002). He also edited Studies in Mathematical Economics (1987), coedited Information, Incentives, and Economic Mechanisms (1987), and serves as Associate Editor of the journals Economic Design and Complex Systems.