During the Middle Ages in Europe, some sexual and gendered behaviors were labeled sodomitical or evoked the use of ambiguous phrases such as the unmentionable vice or the sin against nature. How, though, did these categories enter the field of vision? How do you know a sodomite when you see one? In Seeing Sodomy in the Middle Ages, Robert Mills explores the relationship between sodomy and motifs of vision and visibility in medieval culture, on the one hand, and those categories we today call gender and sexuality, on the other. Challenging the view that ideas about sexual and gender dissidence were too confused to congeal into a coherent form in the Middle Ages, Mills demonstrates that sodomy had a rich, multimedia presence in the period - and that a flexible approach to questions of terminology sheds new light on the many forms this presence took. Among the topics that Mills covers are depictions of the practices of sodomites in illuminated Bibles; motifs of gender transformation and sex change as envisioned by medieval artists and commentators on Ovid; sexual relations in religious houses and other enclosed spaces; and the applicability of modern categories such as transgender, butch and femme, or sexual orientation to medieval culture. Taking in a multitude of images, texts, and methodologies, this book will be of interest to all scholars, regardless of discipline, who engage with gender and sexuality in their work.