Though the creation of European posts and careers is certainly one of the most tangible expressions (and at the same time one of the mainsprings) of European construction, it however remains to be seen in what way these posts are “European” and in what way they are “Europeanising” themselves. In the absence of statistic studies, we know little about the objectivization of Europeanization processes in heavy careers or socio-professional structures. Can we actually speak of a Europeanization of political and administrative careers? If so, what does it consist in and what are the possible and tangible indicators? Moreover, is it a continuous and equal process according to the positions, nationalities and European political sectors? If not, what varies and what can we say about the socio-political conditions of these variations? These questions can find a first group of answers when confronted to the case empirically limited represented by the prosopography of the Directors General of the European Commission.