Defects brings together essays on the emergence of the concept of monstrosity in the eighteenth century and the ways it paralleled the emergence of notions of sexual difference. Women, declared a mid-eighteenth-century vindication, have been regarded since Aristotle as deformed amphibious things, "neither more or less than Monsters" (Beauty's Triumph 1758). This alliance of monstrosity with misogyny, along with the definition of sexual difference as aberration, is the starting point for this volume's investigation of monstrosity's cultural work in the eighteenth century and its simultaneous mapping and troubling of the range of differences. This collection investigates the conceptual and geographical mapping of early modern and Enlightenment ideas of monstrosity onto a range of differences that contested established categories. The essays consider the representations and material dimensions of phenomena as diverse as femininity and disfigurement, the material imagination and monstrous birth, ugliness as an aesthetic category, deafness and theories of sign language, and the exotic, racialized deformed. Collectively, they demonstrate that the emergence of sexual difference is inextricably intertwined with the emergence of a category of the human that is imagined and deformed, monstrous, and ugly.