Abstract
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.