This thesis explores the intertwined histories of abortion and sex work in late nineteenth-century Chicago, a time and place in which both forms of illicit sexuality were paradoxically criminalized yet prevalent. While it was illegal to practice abortion and transmit reproductive knowledge, Chicago sex workers continued to seek abortions and share their knowledge of abortion with others. I first examine the linked discursive methods through which physicians and newspapers communicated information about both abortion and sex work to the wider public. I then piece together the landscape of how sex workers accessed abortion during a period of criminality, arguing that sex work was another covert method through which abortion knowledge could be shared and put into practice. Finally, I explore how physicians used the language of health and medical expertise to regulate illicit sex and maintain authority over reproductive medicine, beginning with the criminalization of abortion and finally coming to fruition with the closing of Chicago’s most notorious red light district in 1912. Ultimately, I argue that sex workers were medical practitioners in their own right, who performed abortions themselves, navigated the city’s interconnected geography of brothels and doctors’ offices to access abortion, and shared their knowledge of abortion with the wider public despite criminalization.