This article presents a model-type of the « unitary » institutionalized faction within the FEN teachers’ union. Although a minority group, its solid presence in the union reveals its flexible identity. In the “unitary” faction, there exists a tension between the FEN agenda and its own priorities, which were once represented by the FEN-CGT. Even if, in granting priority to women and young people, it makes voluntarist claims, it still remains loyal to the pragmatism of the FEN agenda. Its characteristics include a distinctive organization and program of action as well as an hostility towards any overly rigid system of operation. Although it is a real union faction, it is nevertheless marked by a communist matrix. The interference of the French Communist party (PCF) varies according to the period as well as the views of the communist and non-communist teachers. Pacifist, anti-colonialist, it embraces the secular-republican ideology of its milieu, but still separates itself from anticlerical sectarianism. Far from embodying an alternate revolutionary union model, this institutionalized faction constitutes a strong-armed version of the FEN model.