In numerous and diverse medieval texts women use gender disguise to participate in such male activities as monastic life, ecclesiastical governance, travel, business, rescue missions, and warfare. A hitherto overlooked topic, female cross-dressing is so widespread in medieval literature and, to a lesser extent, history that feminine stereotypes, women's roles in literature, and the perception of women in the Middle Ages must be reexamined in light of this phenomenon. As alternative models for female heroism, disguised women combine traditional feminine virtues with male qualities such as adventuresomeness, strength, and perseverance. Paradoxically, however, the empowering force of male disguise reveals the limitations imposed upon women in medieval society since their success is contingent upon suppression of female identity. Moreover, emphasis on the femininity of women in disguise often betrays biases against women; according to many sources women are exemplary precisely because they strive to be like men. This study of medieval cross-dressing covers the following topics: the symbolism underlying the popular vitae of transvestite saints; the confluence of hagiography and biography in the historical case of Hildegund von Schonau; the legend of the female pope and its diverse interpretations before and during the Reformation; the phenomenon of disguise in secular literature, particularly tales of wives and lovers who use disguise to rescue men or regain their affections; and, finally, extraordinary cases of female protagonists in courtly romance who experience a crisis of sexual identity. In these discussion, literary analysis is combined with sociological and historical approached to explore the wide range of meanings and manifestations of transvestism in the Middle Ages.