Donald A. Walker is University Professor and Professor of Economics Emeritus at Indiana University of Pennsylvania. He is the author of Walras's Market Models (Cambridge University Press, 1996), Advances in General Equilibrium Theory (1997), and many articles and reviews in professional journals, chapters in collections, and entries in handbooks and encyclopedias. Professor walker is the editor of William Jaffe's Essay's on Walras (Cambridge University Press, 1983), Money and Markets: Essays by Robert W. Clower (Cmabridge University Press, 1984), Equilibrium (3 vols., 2000), The Legacy of Leon Walras (2 vols., 2001), and, with J.-P. Potier, of La Correspondance entre Aline Walras et William Jaffe (2004), among other works. He was President of the History of Economics Society in 1987-1988, Editor of the Journal of the History of Economic Thoughts from 1989-1999, and the first President of the International Walras Society, 1997-2000.