This article examines some of Langlois's major works on nineteenth-century French Catholicism, which taken together suggest a vision langloisienne defined by three central, intimately interrelated insights. First, for Langlois a chronology of French Catholicism based on an assumption of an ineluctable process of dechristianization needs to be replaced by a more nuanced and contingent understanding of the evolution of belief and practice. Second, a revised chronology illuminates important sectors of creative vitality within Catholicism, particularly with regard to female religious congregations. Third, historians of religion must be willing to use a variety of methods in exploring their subject; social scientific approaches are crucial, but they complement rather than replace traditional narrative, biography, and a close reading of literary texts. The article concludes with reflections on the normative posture that is implicit in Langlois's historical writing, a position based on his commitment to the values of toleration and equality.