This volume contains papers in the broadly defined area of microeconomic theory that were presented to the International Economic Association Tenth World Congress in Moscow. After an introduction, the book begins with Grodal's plenary lecture on profit maximization in the theory of Cournot competition. Then a wide range of topics is covered, from the foundations of economic choice through strategic behaviour (i.e. game theory and implementation), multiple market interactions (i.e. general equilibrium theory) and asymetric information, to applications in such diverse areas as the internal organization of firms, patent policy, product markets and labour supply, finishing with a piece on the history of oligopoly theory. Discussants' comments are included for several sessions. The collection strongly suggests that microeconomic theory is indeed thriving as a fascinating and useful central part of economic science.