There is a paucity of research that illustrates the interplay between HIV/AIDS treatment and prevention programs. We describe the central role that public access to antiretroviral (ARV) medication has played in the development and efficacy of HIV/AIDS prevention programming in Khayelitsha, a resource-poor township in the Western Cape of South Africa. We document the range of preventive interventions and services available in Khayelitsha since the early 1990s and explore the impact of ARV availability on prevention efforts and disease stigma on the basis of extensive indepth interviews, supplemented by data collection. The information gathered suggests that the introduction of the mother-to-child-transmission (MTCT) prevention programs in 1999 and the three HIV treatment clinics run by Doctors Without Borders/Médecins Sans Frontières (MSF) in 2000 were turning points in the region's response to the HIV/AIDS epidemic. These programs have provided incentives for HIV testing, galvanized HIV/AIDS educators to reach populations most at risk, and decreased the HIV incidence rates in Khayeltisha compared to other areas in the Western Cape. Lessons learned in Khayelitsha about the value of treatment availability in facilitating prevention efforts can inform the development of comprehensive approaches to HIV/AIDS in other resource-poor areas.