This paper falls within the frame of social history of politics which aims at questioning the existence of “groups” by situating them within a social space whose frontiers always need to be defined over time. The French Fourth Republic thus seems to have founded a system of promotion and practices of careers in civil service in which the birth of a general “statute” for civil servants was less important than the way civil servants used and reformed it in practice. Two questions are examined. We first try to have a better knowledge of the mechanisms of the local ladders of the State, which have their own dynamic and temporality. Under the Fourth Republic, civil servants like postmasters were more influential than is admitted by some sociologists. Secondly, we examine how civil servants defined their missions by a change in the scale of observation, for example, that postmasters had a real influence on their own careers, their professional itineraries were specialized, and that some tasks were enshrined in practice.