Although most of the literature on international regionalism refers implicitly to a polity defined by the “idea of the region” it seldom looks at the genesis of this idea in the context of world politics. This article argues that looking at the historical formation of the regional idea is important not only to have a better understanding of international regionalism as such, but to address the issue of Europe’s specificity within this trend. There has been an on-going debate about the heuristic status of the European Union (EU) within regional studies, underscoring a widening divide between a somewhat self-introspecting field of EU studies and an international regionalism studies one which provides little insight, other than tautological, on the European experience’s singularity. The historical trajectory of the international regional idea shows a fundamental difference between Europe and the rest of world that could explain some otherwise unintelligible structural disparities between the EU and other regional groupings.