Game and Economic Theory studies the interactions of decision makers whose decisions affect each other. The analysis is from a rational viewpoint: every participant would like to obtain the outcome that he prefers most. However, each one has to take into account that the others are doing the same--trying to get what they prefer most. At times this leads to fierce competition; at other times, to mutually beneficial cooperation; and in general, to an appropriate combination of these two extreme behaviors. Game theory, which may be viewed as a sort of "unified field" theory for the rational side of social science, develops the theoretical foundations for the analysis of such multi-person interactive situations, and then applies these to many disciplines: economics, political science, biology, psychology. computer science, statistics and law. Foremost among these is economic theory, where game theory is playing a central role. This volume consists of twenty-two selected contributions to various areas of game and economic theory. These important and pathbreaking contributions are all by former students of Robert J. Aumann, to whom this volume is dedicated. The volume will no doubt shed light on the far-reaching pertinence of game theory and its application to economics, and also on the monumental impact of Aumann on this discipline. Sergiu Hart is Alice Kusiel de Vorreuter Professor of Mathematical Economics and Director of the Center for Rationality and Interactive Decision Theory, The Hebrew University of Jerusalem. Abraham Neyman is Professor of Mathematics, The Hebrew University of Jerusalem, and Leading Professor of Economics and Mathematics, State University of New York at Stony Brook.