The European greens are often cited as an example of a successful conversion to Europe (Dietz, 1997; Bomberg, 1998, 2002, Bomberg and Carter, 2006; Grimaldi, 2013, 2018, 2020). Indeed, the first Green groups declared their opposition to the European Communities, which they saw as a colonialist and capitalist machine. MEPs and their collaborators engaged into a political resistance within the European Parliament, which they rather sought to open to social movements. However, the greens slowly imposed themselves in the field of Eurocracy (Georgakakis, 2013), abandoning their primary anti-EU positions. Placing the idea of "europeanization" at the heart of their explanatory framework, the research on that question fail to grasp the effects that the variation in political socialization have on the evolution of the actors’ practices and representations. I will show how the use of mixed methods, designed to understand and to objectivize the socialization of these actors, can be used to propose an alternative view to the institutional analysis. This proposition is based on interviews (n=75), ethnographic observations, as well as on a prosopographical database containing about 500 entries (179 MEPs and more than 300 collaborators) and around 40 variables (sociographic data, political mandates, educational and professional careers, etc.). I will show how the divergences in the socialization and politicization of the groups of actors prior to their entry in the EP, together with the position of the parliamentary group within the EP and the European field seem to be a more heuristic entry to the question of political change. While the individual practices and representations of Green actors evolve gradually over time, shaped by their professional and political socialization within the European Parliament, the broader transformations observed in the Green group appear rather to reflect shifts resulting from changes in the political socialization of incoming MEPs and collaborators.
