Drawing on a case study, the article develops a processual analysis of the commitment in the French labor confederation Force ouvrière. It interrogates the political socialization effects of an activist commitment that takes its legitimacy by distancing itself from politics. It shows how political defiance, first facilitates, then impedes a unionist’s career. It also shows how union learning and socializing develops an increasing interest towards politics. However, the union standpoint from which social agents build their relationship to the political world makes highly improbable that the existing political parties be seen as a satisfactory response.