Subject associations appeared in France at the very beginning of the 20th century, bringing together teachers "specialized" in one subject, usually members of secondary public schools. They were positioned at the crossroads of corporatism – since they defended the private interests of one category of the teaching profession – and pedagogy - as they defended and promoted a particular subject. In this issue of Histoire de l'éducation, the thematic part examines the way these associations contribute to the construction of a shared professional culture constitutive of professional identities, and participate in the governance of the educational system. It highlights the way these associations share the field of teacher militancy with other organisations: teacher unions, educational movements, professionnal associations, etc. This issue opens new prospects concerning the transformations of the educational system, the teaching profession and its diverse forms of militancy during the 20th century.