In the last decade, regionalism appears to have emerged as a major new force in the world. This book puts it in its historical context. Regions have emerged before; few are old because they either evolve into federal systems or break up. The current regions are less dominant than their critics fear (they account for about a third of world trade), but imply more integration than a simple view that they are about liberalising trade. All go beyond trade to other linkages, and all the enduring ones have political as well as economic agendas.