My paper proposal is based on my PhD in political science (defended in December 2008) dealing with the genesis, practices and uses of the European Security and Defence Policy with a focus on the comparison between France and Germany both in the genesis and daily practices and representations of ESDP. More precisely, I will focus in my paper on one of the key aspects that I develop in my dissertation: the major impact of the professional socialization in the way that the diplomatic and military actors work inside the new social figuration generated by ESDP both in Brussels and the capitals. Moreover I aim here at focusing on the case of French and German military actors (e.g. officers) working both in Brussels, and Paris and Berlin and daily working in the framework of ESDP (either in the decision-making bodies and the executive organs, or even in the planning of EU operations). My paper proposal would particularly well fit the fourth main theme of the conference on military cultures (challenges of social change and changing nature of operations) and the working group on “The military profession” led by Giuseppe Caforio. Who are these actors? What are their professional trajectories? What kind of personal, organisational and professional resources do they have at their disposal dealing daily with ESDP ? How do they invest these resources, and with which king of career and action strategy? What are the convergences and divergences in this matter between French and German officers ? I particularly rely on theoretical resources crossing profession sociology, military sociology (mostly Janowitz and Moskos; the studies conducted by Karl Haltiner or by Giuseppe Caforio are of huge interest for me here) and historical sociology (mostly inspired by Norbert Elias in my case). These crossed sociological perspective enable me to analyze who theses officers are socially and in the frame of the military profession (question of their trajectories, of the cross checking of the ESDP networks with the French-German military cooperation networks). I will also analyse to what extent their professional ethos interacts with their national habitus in Brussels. This ethos plays both as a corporatist resource in their interaction with the non-military actors working with ESDP and as a constraint regarding the military actors of different nationalities. As a matter of fact national military culture is still the major referent for these officers according to our finings based on 135 qualitative interviews in Paris, Berlin, Bonn and Brussels. This military culture is mostly secreted by the national figurations of defence policy on the long run. There historical sociology helps us understanding the marginal changes in this culture and in the military profession compared with the relative inertia of the deep core of this culture. For instance, though military operations have changed in their very nature for every European army since the 1990's, one can still observe different representations and practices regarding the conception of what it is to be in the army, or the use of force and its justification by the French and German officers. The main advantage in comparing France and Germany here is to observe that in spite of a long tradition of close cooperation in defence policy and military exercises and exchanges, military profession is still much anchored in national military culture, which socializes the officers during the time of their professional formation. I will also as an opening section tackle the question of the marginal European socialization intervening bottom-up through the European operations, such as EUFOR Althea or EUFOR Congo for instance. All theses elements of course come together in the more global framework of the evolution of military profession in the 21st Century faced both with Europeanization, globalization and civilianization movements. Empirically my communication will be based on the 135 qualitative interviews conducted during my dissertation field work.