In twenty years’ time, the clothing of sisters in the Netherlands changed significantly from habit, modified habit to secular dress. By ‘sisters’ I mean female members of Roman Catholic congregations, founded since the beginning of the nineteenth century for work in e.g. nursing and education. The central question in this article is when and how change occurred, what the underlying causes were, and how changes were implemented, substantiated, interpreted, and experienced by sisters. The congregation boards took the contemporary social developments into account and implemented renewal of clothing in decisive steps, fitting their own goals. Carrying out research in archives of four congregations revealed differences in argumentation, process, and outcome. It also brings to light how, in the course of two decades, the mental world of sisters changed: from a closed cloister mentality to openness to the world.