Sexology emerged as a discipline during a period of keen concern about the social effects of sexually explicit media. In this context, sex researchers and their allies took pains to establish the respectability of their work, a process that often involved positioning sexual science in opposition to erotic literature and images. This article argues that this presentation of sexual science obfuscated sex researchers’ complex relationship with erotic print culture, which during the late 19th and early 20th centuries provided sexual scientists (...) with access to explicit material that served as evidence for theories about human sexuality, facilitated transnational exchanges of sexual-scientific thought by bringing sex research across borders, and introduced sex research to wider audiences. Erotic print culture can thus be seen as one of several fields that contributed to the interdisciplinary development of sexology and facilitated the diffusion of sexual-scientific theories. Sex researchers’ shifting, often ambivalent relationship with erotic print and its producers emphasizes that while the boundaries of sexology were extremely porous, they were also heavily policed: Working to establish a modern, respectable new branch of science, sexual scientists reframed the output of other fields of enquiry as products of their own, blotted their reliance on these sources from the historical record, and denigrated them in public writing. (shrink)