The purpose of the course is to provide an introduction to the principles and norms of international law applicable to the inter-governmental organisations (IGOs). It discusses the essential topics of the law of international organisations, including powers, privileges and immunities, as well as membership rules, institutional structures, and accountability. There is a focus on the United Nations system, as the paradigmatic IGO, including the activities of the specialised agencies based in Rome. Special emphasis is placed on the interaction between universalism and regionalism. IGOs have developed into a pervasive phenomenon: a fundamental objective of the course is to develop a critical understanding of their impact vis-à-vis the current global challenges (economic and financial crises, migration, armed conflicts, disarmament, natural disasters, epidemics).