This two-year award in support of U.S.-France collaborative research in economics involves Russell W. Cooper of the National Bureau of Economic Research and Hubert Kempf of the Universite de Paris 1 (Sorbonne). They will investigate the costs and benefits of monetary union and the optimal structure of a monetary union in terms of the number of members and their characteristics. Their preliminary research on the economic gains of monetary union will serve as a model for this project on costs and benefits. The US investigator brings to this collaboration extensive experience in macro- economic research. This is complemented by theoretical input from the French investigator and his institutional knowledge of France and the European Union. The collaboration will advance our understanding of the trade-offs involved in adopting a common currency and the proper operation of a monetary union as we enter this new age of global economies.