The aim of this article is to demonstrate the usefulness of taking into account the variable of EU institutional development when analysing the consequences of EU membership. Using an historical institutionalist perspective, the article examines the path of the Council Presidency since its origins and argues that five decades of institutional feedback have unexpectedly altered its nature. Originally conceived as an intergovernmental function, today the Presidency has become hybrid and increasingly identified with the Community interests. This process of institutional conversion has essentially limited the scope of action of the member states.