This article evaluates the influence of Claude Langlois's research on female religious congregations in the field of women's history. It explores how his central findings contributed to scholarship on the feminization of religion before generating a strain of revisionist historiography concerning the history of girls' education and the history of the nursing profession and health care. Specifically, Langois's work has led scholars to investigate the archives of religious congregations and evaluate the emergence of a professional ethos among teaching and nursing nuns. The article concludes with an analysis of his more recent writings on missionary congregations and how this also has inspired work on the gendering of religious mission.