This book is a detailed study of the female members of the Order or Hospital of Saint John of Jerusalem in the High Middle Ages. It analyses their presence in the context of female monasticism and compares their position to the position of women in other religious military orders. The study is distinct not only because its topic has never before been addressed in a monograph, but also because of its cross-fertilizing approach: It introduces questions of gender into the history of the military orders and it relates answers to these question to the history of female monasticism, bringing fresh insights to both.