This article retraces the evolution of the educational system of the CGT by focusing on its similarities with and differences from other forms of education: partisan political education (specifically in the Communist Party), public education, and professional training. The findings are based on documents from the archives of the Centre confédéral d’éducation ouvrière of the CGT, which have never been analysed, as well as on interviews with former members of this Center who know a great deal about the content and methods of CGT education. The article reveals the relative autonomy of those persons in charge of education, and analyses their practices as well as their syndical, intellectual and social trajectories. It proposes a way to periodize the evolution of CGT education: from a “syndicalization of education” beginning in 1947 to “life-long syndical training” in more recent years.