This dissertation analyzes the political, economic, and socio-cultural processes that have shaped the Afro-Brazilian religious mobilization around HIV and access to healthcare. The extended case study provides important insights about how social movement organizations can mobilize resources, take advantage of political opportunities, and harness power in collective identities. Bringing together several theories that postulate why religious groups may be successful in incentivizing collective action, I focus more intently on Manuel Castells' theory about identity politics—showing the process of a historical transformation from "legitimizing identities" to "project identities" in the Afro-Brazilian religious mobilization. The three major areas of analyses refer, first, to how the Afro-Brazilian religious health social movement has affected AIDS policy because of political opportunities (democratization, constitutional mandate, executive and bureaucratic organization, etc.) and resource availability (i.e., networks, funding, and entrepreneurs). Ties with non-governmental organizations (NGOs) that work with AIDS have facilitated the use of the Afro-Brazilian religious institution as a cultural and physical space for mobilization. The second area of analysis highlights the historical transformations in public health interventions that take into account cultural and structural vulnerabilities. The politics of inclusion in the AIDS social movement have drawn from the principles of solidarity and citizenship. Third, the dissertation explores whether a collective identity based on ethnicity and religion, primarily, can effectively forge coalitions between social movements to shape policy and mitigate stigma. The mobilization of religious leaders, spaces and networks has been crucial in advocating on behalf of affirmative action measures, especially impacting research agendas. The analysis presented here is a significant contribution to policymaking and AIDS activism. As the National AIDS Program continues to decentralize and become incorporated in the Unified Health System, the Brazilian response to AIDS is increasingly considering religious groups as important institutions for reaching marginalized populations and politicizing vulnerability.