This volume is the result of a conference held at the Institute for Advanced Studies, Vienna. There is still a gap reflected both in fundamental meth odological differences and in the style of analysis between the Walrasian (and Edgeworthian) tradition of general equilibrium theory and the theo retical and policy problems raised in the framework of Keynesian and post-Keynesian macroeconomics. The conference succeeded in bringing together economic theorists working in fields ranging from abstract prob lems of mathematical equilibrium analysis to applied macroeconomic theory, and it is hoped that the present volume will contribute to bridging the above-mentioned hiatus.