Project Summary The District of Columbia Clinical Trials Unit (DC CTU) will conduct clinical trials for persons with and at risk for HIV in DC, where 1.8% of the overall population and 2.7% of the African-American population are living with HIV. The DC CTU will unite two existing, high-performing DAIDS/NIAID Clinical Research Sites (CRS), the Whitman-Walker Health CRS and the George Washington University CRS, in a new CTU, participating in the HIV/AIDS Adult Therapeutics and HIV Prevention Clinical Trials Networks. Our innovative and geographically- focused DC CTU will ensure exemplary clinical trials management, recruitment, and retention of a diverse sample of participants, with a community engagement strategy built on existing partnerships and Good Participatory Practices. The DC CTU will achieve four specific aims: 1) Provide scientific leadership and administrative infrastructure to allow high-quality conduct of therapeutic and prevention studies at two established CRSs; 2) Implement best practices to ensure continued high recruitment and retention rates; participant safety; and laboratory, pharmacy, data, and regulatory excellence; 3) Actively engage with the local community to ensure optimal enrollment of diverse participants from within and beyond clinic settings using Good Participatory Practices; and 4) Capitalize on the resources available from the DC CFAR and DC Cohort to engage senior investigators, mentor investigators in clinical trials conduct, and access a broad array of services to address NIH and network scientific and programmatic priorities. The DC CTU will engage participants who can benefit from innovative clinical trials while we contribute to high-quality participatory research that will eventually end the HIV epidemic.