This paper explores how fragile masculinity has been portrayed in Medieval and Renaissance literature by analyzing the impact of female-crossing dressing on male characters in Heldris of Cornwall’s Le Roman de Silence and William Shakespeare’s Twelfth Night. In the 13th century French Romance that centers on the debate between nature and nurture, Silence is a female raised as a male to circumvent patrilineal inheritance laws who becomes a celebrated knight. In Twelfth Night, Viola cross-dresses as Cesario, an act that results in the unintentional winning of Olivia’s love as well as confused (and ultimately resolved) romantic feelings from Count Orsino. By disrupting the traditional gender expectations for women and succeeding in masculine spaces, Silence and Viola reveal the malleability of the constructed gender binary, the complexity of the concept of “nature,” and the fragility of other cultural categories, particularly socioeconomic classes. Both texts are implicitly subversive by creating a sense of distance by using an ironic narrator or a carnivalesque inversion, and both end in culturally necessary stabilizing gestures that on the surface, undercut the subversive messaging. However, the successful crossing of the gender boundary highlights the superficiality and flexibility of the boundaries themselves, resulting in enduring subversion