Since the end of the 1980s, international relations has experienced a resurgence of regionalism in Europe (Single Market, Maastricht) and the Americas (NAFTA, MERCOSUR). Why did regional economic cooperation gain mo mentum? Theoretical approaches have proved the relevance of institutions, intergovernmental bargains, and na tional interest formation for the emergence of cooperation, but fall short in explaining why new cooperative moves happened in the late 1980s and early 1990s and not earlier. This paper argues that the simultaneous convergence of interests favoring regional organization of states was stimulated by transnational globalization. Since the early 1980s, states had to adapt to the pressures from transnational globalization, from actors and systems which are not shaped by national territories and interests, and which undermined traditional national economic policy and domestic coalitions. Under the new circumstances, joint regional governance on specific policy areas became an attractive option to respond to new constraints. With the conceptualization of transnational globalization as an explanatory factor for regional cooperation this paper does not dismiss other approaches, but rather attempts to complement the research agenda by shedding light on a crucial-but often neglected-aspect of international relations.