Scholars are currently giving serious thought to Thomas Aquinas’s theology of religions. This fact led the author to explore the connection between Aquinas’s thought on the subject and that of the Neo-Thomists of the 19th and 20th centuries. Starting from the analysis of textbooks, he illuminates the structure of the theology of religions that characterized Catholic culture in Belgium and the United States from 1870 to 1950, and the continuity and discontinuity of it with Aquinas’s thought. He thereby also illuminates Vatican II’s approach to interreligious dialogue.