When Nicholas of Cusa (1401-1464) writes that distinctions between masculine and feminine collapse into a "coincidentia oppositorum" [coincidence of opposites] as they approach the threshold of paradise and Bernard of Clairvaux (1019-1153) interprets the Song of Songs as figuring Christ as both a Bride and the Bridegroom, they join other spiritual writers in positing what is today called "non-binary gender" as an aspect of the divine. In this dissertation, I argue that certain medieval English hagiographers engage in a project of representing the ways in which this aspect of the divine might enrich a saint's pursuit of holiness. I analyze this type of narrative, often called the "cross-dressing saints' life," using examples from The Old English Martyrology, Ælfric's Lives of Saints, The Northern Homily Cycle, saints' lives contained in two well-known literary manuscripts, British Library MS Harley 2253 and Oxford Bodleian Library MS Eng. Poet. a. 1, also known as the Vernon Manuscript, Gilte Legende, and Caxton's early print translation of Jacobus de Voragine's Golden Legend. I demonstrate that authors and scribes in medieval England understood identity as capable of moving beyond the gender binary in a spiritual context, which they explored through the narratives of saints who exhibit both masculine and feminine identities.In this project, I also demonstrate the intellectual engagement with non-binary gender by authors and scribes through an analysis of the linguistic, literary, and rhetorical tools they use to create these identities. The Vernon Manuscript, which has not yet been studied for its inclusion of several gender non-binary saints' lives, presents these texts alongside other representations of gender in religious life, prompting its likely audience of women religious to consider the complexity of their own gender identities in relation to their spiritual occupations. By developing a greater understanding of the role of non-binary gender in medieval English religious culture, I challenge the notion of the gender binary as a foregone conclusion in Anglophone cultural heritage. Furthermore, I show that non-binary gender as it develops in these narratives adds nuance to our understanding of gender diversity as well as the intersectional relationships between gender, language, spirituality, and culture in medieval Britain.