This dissertation seeks to redefine late-nineteenth-century American literary naturalism as a movement that is continually negotiating the tension between speculative fantasy and scientific objectivity, a tension that both reveals and is revealed by naturalism's voyeuristic gaze. This interdisciplinary project brings together novels and paintings to examine the ways that this voyeurism was dramatized and enacted by the literature and art of this period, as well as served as a method for critiquing the preeminent role that vision played in constructing knowledge in the nineteenth century. Foregrounding the scopophilia of the late nineteenth century and its representation in novels such as Stephen Crane's Maggie, Frank Norris's McTeague, Theodore Dreiser's Sister Carrie, and Edith Wharton's The House of Mirth, as well as paintings by Thomas Eakins and Ashcan School artists, makes manifest naturalism's complex portrayals of asymmetrical visual authority, including unequal configurations of class hierarchies and challenges to traditional representations of sexuality and gender. These works become sites through which we can read the fantasies of class, of masculinity, and of sexuality that were integral to the experience of the nineteenth century but have often been obscured by claims of formal realism. Naturalism's attempts to create a detached spectator reveal the impossibility of realist objectivity, and this failure engenders the radical subjectivity found in twentieth-century modernism. Although naturalism attempts objectivity through its subjectivity, modernism reveals the impossibility of this project even while celebrating this failure. In this way a full appreciation of literary naturalism's voyeuristic gaze reveals the tensions inherent to the movement itself while simultaneously illuminating the influential legacy of naturalism in twentieth-century modernism.