Beginning with this Review, the World Economy chapter contains a number of changes in format and content. The first half of the chapter presents the main forecast, which for the first time is produced with the aid of a quarterly econometric model, GEM. The second half of the chapter will be devoted to one or more topical issues concerning the world economic outlook, using analysis based on econometric evidence or model simulations. In this Review we look at the prospects for the US current balance. An appendix briefly outlines the structure of GEM.