ABSTRACT
The study of the institutionalization process of international relations is deeply rooted in the history of the discipline. The empirical description of international organizations belongs to the very origins, immediately after the First World War and the foundation of the League of Nations. However, focusing on the theoretical issues linked to the relationship between state-sovereignty and international institutionalization as a broad process took some time. This chapter examines both early theoretical trends after the Second World War and more recent developments of institutionalist approaches to international relations: firstly, two relevant schools of thought which were particularly developed in Europe and in the US after the Second World War and, secondly, the theoretical neo institutionalist debate taking place since the 1980s and 1990s.
