The Organization of American States (OAS) is a regional multilateral organization made up of the sovereign states of the Western Hemisphere. The author describes its charter, organization and history, then focuses on pathbreaking efforts to support democracy that were subsequently severely hampered by lack of resources, political conflicts, and the disengagement of key members, especially the United States. He then analyzes the three organizing concepts of the OAS and of international organization more generally: multilateralism, geography and sovereignty, and finds each of them challenged by contemporary developments. He concludes that multilateralism remains essential and that geography and neighborhood still matter, but that sovereignty should be understood as setting the terms for working with others, rather than as a basis for rejecting cooperation. To maintain sovereignty, countries must deal with the outside world, their neighbors perhaps most of all. And all – small and large, large and small – must contribute their share.