This article provides an overview of the institutionalization of the European Parliament. Quantitative analysis, based on the biographies of Members of European Parliament on the sixth term (between 2004 and 2009), underlines the emergence of specialists who dominate the parliamentary space. First, we point out convergences in the modalities of political and social recruitment. The unattractiveness of the European Parliament (EP), compared to the national political space, has favoured the recruitment of actors who are less endowed with legitimate resources. For numerous members, the EP represents an opportunity for political professionalization. Second, we underline the emergence of a parliamentary elite with specific European resources and career types.