The history of “Études de théologie, de philosophie et d’histoire” is connected with the Work of Saints Cyril and Methodius (L’OEuvre des Saints Cyrille et Méthode), which was founded in 1855. The purpose of the Work was prayer as well as refl ection and discussion on the union of the Catholic and Orthodox Church. The founder of the Work, Ivan Gagarin, once Russian Orthodox and from 1842 a Catholic in France, gathered for this purpose a vast library in order to document the history of ecumenism and the ecclesiastical history of the Slavic countries. With time, the Slavonic Library became one of the most abundant book collections on these subjects in Western Europe. Gagarin believed that the West knew too little about the Orthodox Russia, which was an impediment to the union of the Churches. To bring his motherland closer to Western Catholics and to present problems to be faced by those who strove for the unity of the Christian East and West, Gagarin decided to start to publish a magazine “Études de théologie, de philosophie et d’histoire”, for which he needed approval of the superiors of the Jesuit Order. Due to Gagarin’s prolonged negotiations with his superiors, the magazine did not start to be published until 1857. This paper deals with the history of “Études de théologie, de philosophie et d’histoire”.