From the principle of state sovereignty to United Nations bureaucracies, international relations are organized by a variety of norms and institutions. After tracing the history of international organization (IO), as well as the intellectual development of its study, we conceptualize IO in terms three levels of formality: IO as formal organization, IO as regime, and IO as ordering principle. We emphasize rationalist approaches - including cooperation theory, associated theories of regimes, and the new institutional economics - as the ones most closely connected to law and economics. After discussing this broad perspective, we consider emerging approaches to international institutional design. Overall, we document a convergence among economists, political scientists and international legal scholars reflected in methodological approach and substantive interests.
JEL classification: K33, A12, D70, F02, D23
Keywords: International Organizations, Regime Theory, New Economics of
Organization, Cooperation Theory, Institutions, International Politics
