This dissertation discusses medieval and Renaissance clerical and cultural constructions of femininity and female masculinity, and it analyses the complex relationship between such conceptions and the literary representation of the transvestite woman. Medieval theology legitimated female masculinity as transcendence of temporal sexuality. A woman who contained her affective femininity and replaced it with rational and ascetic behaviour was frequently lauded for having become male in all but body. In the middle of the first millennium, hagiographic legends abounded in which women appear to have embodied the patristic equation between spiritual rationality and masculinity. This dissertation proposes a radically different interpretation: the saint exchanges a sexualised form of femininity--ironically imposed upon her by a male society--for a non sexual but nevertheless feminine self valuation.