The main purpose of the Handbook of Utility Theory is to make more widely available some recent developments in the area. The editors selected a list of topics that seemed ripe enough to be covered by review articles. Then they invited contributions from researchers whose expert work had come to their attention. So the list of topics and contributors is largely the editors’ responsibility. Each contributor’s chapter has been refereed, and revised according to the referees’ remarks. Whereas Volume I of the Handbook of Utility Theory is largely concentrated on basic theory, the present volume is concerned with extensions and applications to other branches of economic theory. Taken together, these first two volumes contain all the purely theoretical material that the editors planned to cover. The chapters on experimental and empirical research on utility and the chapters on the history of utility theory will appear in Volume III.