The objectives of the CPCRA Clinical Trials Unit (Community Programs for Clinical Research on AIDS) are: to conduct clinically relevant research in the prevention and treatment of HIV disease and its complications; to involve in clinical trials a demographically, geographically, and socio-economically diverse population of individuals infected with HIV or at risk of infection; and to carry out this research agenda in close collaboration with community members who are themselves infected with or affected by HIV. The CPCRA CTU will make significant contributions to the INSIGHT and HIV Prevention Trials (HPTN) networks, both in enrollment and in scientific expertise. Through INSIGHT, the CPCRA CTU will contribute to multiple, randomized clinical trials in order to help determine the optimal clinical management for persons who are HIV+. These trials include studies of those who are: highly-antiretroviral (ARV) experienced and for whom virologic suppression cannot be achieved and maintained; ARV-naive, with advanced HIV disease and presenting for care with an opportunistic infection; co-infected with HIV and hepatitis virus; or at moderate-to-high risk of cardiovascular disease. Through the HPTN, the CPCRA CTU will contribute to trials examining both behavioral and therapeutic interventions with behavioral and biologic outcomes, seeking to reduce HIV transmission and HIV transmission-risk behavior. Targeted populations include those who are HIV+, as well as those who are HIV- and at-risk for seroconversion, such as injecting-drug and cocaine users and others at risk for seroconversion through sexual contact. The Executive Office of the CPCRA Clinical Trials Unit, located at the Veterans Affairs Medical Center in Washington DC, is an off-campus affiliate of the applicant institution, The George Washington University. The Principal Investigator and Executive Office staff provide oversight, central coordination, training and education, technical assistance, and regulatory support for its 137 CRSs, organized by region into 23 Site Coordinating Centers (SCCs) in the United States, Brazil, Canada, Peru, and South Africa. These sites have in care a cumulative, demographically diverse patient base of over 152,000 persons with HIV/AIDS. HIV is a major public health problem around the world. It is important to find better ways to use the medicines that we have to treat HIV, so that people who are infected can live longer and healthier lives. It is also important to find better ways to stop the spread of HIV by doing studies with people who have HIV infection and people who don't have HIV but who are at risk for getting HIV infection. ADMINISTRATIVE COMPONENT: