Donald E. Campbell is CSX Professor of Economics and Public Policy at William and Mary College, Williamsburg, Virginia, where he has taught since 1990. He previously served as Professor of Economics at the University of Toronto from 1970 to 1990. He is the author of Resource Allocation Mechanisms (Cambridge University Press, 1987), and Equity, Efficiency and Social Choice (1992). His published research has appeared in leading journals such as Econometrica, the Journal of Political Economy, American Economic Review, the Journal of Economic Theory, Review of Economics Studies, and the Journal of Mathematical Economics.