Pre-exposure prophylaxis (PrEP), which contains a combination of tenofovir and emtricitabine, has emerged as a new biomedical HIV prevention option. Multilateral groups and health policy makers have called for demonstration projects to better understand PrEP’s everyday use and effectiveness. Funded by the Bill & Melinda Gates Foundation and in partnership with the University of Manitoba, Ashodaya Samithi, a sex worker collective, initiated a PrEP demonstration project in Mysore and Mandya, Karnataka State, South India. Drawing on qualitative ethnographic methods, a study of the PrEP demonstration project took place between January 2015 and April 2018 and included field visits, participant observation, and in-depth interviews with demonstration project participants and the implementation team. Community researchers and I conducted 167 interviews over the course of the study. Following a community validation and contextualization (or “member checking”) session, I coded the data for key themes and emergent categories. According to the biomedical indicators of retention and adherence, the demonstration project proved immensely successful, with 640/647 participants retained for the 16-month project and participants reporting high adherence confirmed by blood-level tenofovir testing. Attempting to more fully account for how this “success” arrived, however, I go beyond these biomedical interpretations of retention and adherence, pointing instead toward Ashodaya’s history of collectivization around sexual health—a history of community action that has given rise to forms of health citizenship and new spaces of belonging for sex workers. In what I call the “search for success”, a particular attention is placed on the role that care plays among Ashodaya sex workers over the life course of the demonstration project. This care is tied not only to the community of sex workers Ashodaya seeks to serve, but also to the careful production of evidence that demonstrates accountability to funders, which is, furthermore, tied to caring for the very survival and future of the organization.