Regionalism has become a global phenomenon. As international interdependence continues to grow, countries increasingly seek institutionalized cooperation with neighbouring states to tackle pressing problems such as environmental degradation, migration flows, and developmental challenges. The list of regional organizations is long. Among the more well-known ones are the North American Free Trade Agreement, Mercosur in South America, the Southern African Development Community, the Association of Southeast Asian Nations, and the European Union (EU). But there are many more. Have you heard of the Pacific Island Forum? The Organization of Eastern Caribbean States? Or the Intergovernmental Authority for Development? Today, there is barely a region in the world that does not feature a regional organization.
In the academic study of regional organizations, scholars have mainly focused on explaining the differences between them. Why are some more institutionalized than others? Why are some more successful than others, etc.? Less attention has been paid to understanding commonalities. Many of these organizations were created around roughly the same time: a first wave emerged in the 1960s, a second wave followed in the early 1990s. Many economics-oriented regional organizations pursue the ambition to create EU-type common markets and customs unions. Marked similarities in institutional arrangements exist. For example, 11 organizations have created a regional court along the lines of the European Court of Justice (Alter, 2012). Finally, many regional organizations have seen a continuous evolution over time, moving away from traditional models of intergovernmental cooperation towards more supranational forms of governance. These phenomena are central to our understanding of regionalism.
Diffusion theory draws particular attention to such commonalities, and the EU as the most prominent pioneer plays a special role in this broader panorama of regional organizations. This article explicates how diffusion theory can serve as a useful analytical tool to examine the EU’s influence on regionalism elsewhere.