This article examines the reasons for the secularization of most Protestant schools in France after the promulgation of the Jules Ferry Laws (1881-1882). In particular, it seeks to understand why 1,000 of the 1,535 schools of the “Société pour l’Encouragement de l’Instruction parmi les Protestants de France” (SEIPF) became secular public schools in 1882. And why did the Society, once a frontline actor, recede into the background? Does it suggest approval of Ferry’s views, thereby confirming the notion of French secularism as a ‘daughter of Protestantism’? Or was it rather a circumstantial effect that must be explained in light of the Society’s history?