Medieval tales of father-daughter incest depict more than offensively dominant fathers and voiceless, victimized young women: these stories often contain moments of surprising counternarrative. My analysis of incest narratives foregrounds striking instances of feminine resistance, where daughters act independently, speak unrestrainedly, adopt masculine behaviors, and invert masculine gazes. I argue that daughters of incestuous fathers participate in a complex back-and-forth of attraction and rejection that thrusts the fraught nature of the incest into sharp relief, revealing the ways in which medieval families--as well as the medieval church and state--constructed and deconstructed identities and sexualities. Extending Judith Butler's insights on how incest tales interrogate state and kinship networks, I show how the liminal position of daughters in the family destabilizes the sex/gender system as it functioned in both the family and the larger world, secular and sacred. My dissertation thus relocates daughters from the periphery to the center of the medieval family. Christian thematics likewise provide a key framework for both my argument and medieval audiences: biblical translations and retellings, saints' lives, and moral exempla offered familiar points of reference. By revealing how authors and artists employed well-known religious stories to impart political readings of sexuality and of the family, the four chapters of my dissertation assert daughters' key role in medieval Christian culture. I examine both Anglo-Saxon texts--the biblical epic Genesis A and the prose Life of Euphrosyne--as well as the late medieval poem Cursor mundi and Chaucer's Clerk's Tale. My readings are enhanced by recourse to the medieval visual record offered by three manuscripts that illustrate the Lot story--British Library MS Cotton Claudius B.iv, the Old English Hexateuch, and Oxford Bodleian Library MSS Junius 11(the Genesis A manuscript) and Bodley 270b, a Biblé moralisée. Artistic renderings of father-daughter incest are no less unsettled than their literary counterparts, and demonstrate that the position of daughters was so fundamentally unstable that it often varied not only within an era, but also within a single manuscript. I argue that authors and artists radically reimagined the fundamental texts of the Middle Ages, including the Old Testament, to establish new narratives of sin and salvation, self and other, and power and submission.