Worldwide, subject-matter teachers are commonplace in post-elementary schools. Teachers’ specialization appears as a key characteristic of secondary schools as opposed to the polyvalence of primary school teachers. Historians have already studied the long process of teachers’ specialization, which started, in France as in Prussia (for example), at the beginning of the 19th century and developed alongside secondary school modernisation. Those works have usually focused on professional aspects: the structuration of professional groups thanks to the unification of training and recruiting processes, the organization of teachers within subject-matter associations etc. However, they have not paid much attention to the resistance opposed by other forms of pedagogical organization, as if polyvalence was just a remanence, a backward anomaly, doomed to disappear. In this paper, we want to shed a new light on this question using a comparison between the different forms of post-elementary schooling which existed at the same time in France between the last third of the 19th century and the middle of the 20th century, when the slow growth of post-elementary schooling was mainly due to the success of subaltern institutions. In those institutions, dedicated to technical education, girls secondary education, or upper-lower classes education (“primaire supérieur”, “secondaire special”), different kinds of polyvalence or bivalence were experienced in the classrooms. At the same time, specialization was triumphing in classical secondary education. Why, how and to what extent, did specialization eventually impose itself in these different institutions? To address this question, we use two types of material. On the one hand, we study the question on a national level, analysing both the legislation and the controversies it arouses in pedagogical and professional reviews. On the other hand, we confront these views and theories with a prosopography of post-elementary school teachers in one department, Eure-et-Loir, which offers several forms of post-elementary institutions. We address this question focusing on literary disciplines (philosophy, French, Latin, Greek, modern languages and history and geography). By narrowing the scope, we are more able to grasp intellectual and cultural stakes of the various pedagogical organizations that were implemented or advocated. The first part of the article examines the most common – (though relatively untested) – hypothesis: there was just one strategy for those who advocated the promotion of subaltern types of post-elementary schooling as part of a democratization process, and this strategy was reproducing the model of the elite institution, secondary classical education, including its pedagogical organization, starting with subject-matter teachers. The chronology of the changes, the content of the debates, as well as a comparative inquiry into teachers’ remuneration induces us to discard this hypothesis as insufficient if not irrelevant. For girls’ secondary education, we may observe a trade-off between equalization (of salaries, rights etc.) and pedagogical alignment. For the other institutions, there was no lack of advocates for the specificity of the pedagogy or of the institution; however, specialization was usually considered has a process that could ameliorate the quality of teaching in these institutions without renouncing its specificity.In fact, in the period we are studying, the louder advocates for less specialized teachers came from secondary classical education itself: the specialization process as well as the fragmentation of the class schedule had pedagogic inconveniences, abundantly noticed and commented on by subject-matter teachers themselves. In the second part, we examine these critics and the two main alternatives suggested by the teachers. The first one is linked with the Progressive Education movement (“Education nouvelle” in French). The École des Roches, a private institution, tested an original organization which combined the tradition of the humanities with the modern characteristic of “Éducation nouvelle”: there was only one teacher for history, geography, French, Latin and Greek. The teacher was thus enabled to practice a pedagogy of interest, as advocated by Ovide Decroly. The second alternative was advocated by some modern language teachers: if modern language teachers could teach French as well as a modern language, this pedagogic organization could give a strong unity to the until then defective “modern” curriculum (without latin).In the third part, we turn towards the effective organization of post-elementary schools in Eure-et-Loir. To what extent were these alternative conceptions of pedagogical organization implemented? The analysis of individual records of teachers suggests several results. First of all, in small institutions – be it classical secondary institutions like “collèges” or modern ones like “écoles primaires supérieures” – specialization of services was a luxury that most teachers could not afford. Most of the time, they had to teach several subjects, even if they had been trained just for one. However, polyvalence was not used as an opportunity to make connections between the subjects. Class schedules rarely enabled teachers to use polyvalence as a way to teach several subjects to the same pupils. More often, polyvalence was used by the administration as an expedient that some teachers explicitly tried to escape, for example, by asking for a move towards a bigger institution.This mundane reality of small institutions invites us to pay renewed attention to teacher training and its regulation during the same period. At the end of the 19th century, teachers’ specialization had been inextricably linked with the modernisation of universities through the specialization of the “licence de lettres” in 1880. When this model proved to be partially irrelevant for a significant part of post-elementary schools, how did universities react? Were universities fit to something else than training specialised teachers? The answer is yes. The curriculum organization of the licence opened up several possibilities for training polyvalent teachers. This perspective was still looming at the end of the 1930s. The curricula of the different post-elementary settings analysed in this article shared the same characteristics: they worked as “serial codes” not as “integrated codes”, to quote Basil Bernstein. Therefore specialization, bivalence or polyvalence of the teachers did not have much influence, in itself, on the degree of integration of the curriculum. From this perspective, specialization could probably guarantee better teaching of the subject matters. However, polyvalent teachers were better suited to small schools than specialist ones. Considering demographical and geographical constraints, there was a clear trade-off between specialization of teachers and separation of publics. In small cities, you had either to mix the pupils to specialize the teachers, or to accept some kind of polyvalence to keep different types of students separated: the debate was still open during the 1930s. School massification, coeducation, and baby-boom rapidly settled the matter for small cities after the Second World War, giving way to an effective specialization of teachers. But the question laid still open, until the end of the 1970s, for rural settings.< Réduire