College campus-based surveys of sexual assault in the United States have generated one of the most high-profile and contentious figures in the history of social science: the ‘1 in 5’ statistic. Referring to the number of women who have experienced either attempted or completed sexual assault since their time in college, ‘1 in 5’ has done significant work in making the prevalence of this experience legible to the public and to policy-makers. Here I examine how sexual assault surveys have participated (...) in structuring the ontology of date/acquaintance rape from the 1980s to today. I review the foundational work of feminist social scientists Diana Russell and Mary Koss, with particular attention to the methodological practices through which the concept of the ‘hidden’ or ‘unacknowledged’ rape victim emerged. I then examine a selection of early 21st-century sexual assault surveys and highlight the ongoing preoccupation with survey methodology in responses to their results. I argue that the survey itself has been a central actor in the ontological politics of sexual assault, and only by closely attending to its performativity can we understand the paradoxical persistence both of critical responses to the ‘1 in 5’ statistic and of its effective deployment in anti-violence policy. (shrink)