This is an application for a Clinical Trials Unit (CTU) by Harvard School of Public Health (HSPH) (as CORE) and Tanzanian partners at two Clinical Research Sites (CRS), namely Muhimbili University College of Health Sciences (MUCHS) in Dar es Salaam and Kilimanjaro Christian Medical Center (KCMC) in Moshi. At MUCHS, we propose to contribute to the agenda of IMPAACT Network and to the Vaccines priority area. At KCMC, we will contribute to the Microbicides Trials Network (MTN). We will continue to 2 transition studies, HPTN 046 in Dar es Salaam and HPTN 036 in Moshi. The CTU Administrative CORE activities will be primarily located at the HSPH and managed by an Executive Committee assisted by a Scientific Oversight Committee, Site Steering Committees, and Community Advisory Boards. These structures will be supported by an effective communication system between the core and the sites. We have a multidisciplinary team of behavioral, clinical, epidemiological, statistical, and laboratory scientists, at Harvard, MUCHS and KCMC. Through the conduct of several large studies conducted jointly over the past 15 years, we have demonstrated that we can design and implement randomized trials of interventions targeting HIV/AIDS prevention and treatment. We have developed solid infrastructure and experience in laboratory, pharmacy and clinical aspects required for the scientific agendas that we envision contributing to. Our CRS at MUCHS and KCMC are capable of meeting the requirements of conducting Network clinical trials, and will be able to do so within 6 months of an award. Research has been, and will continue to be undertaken by highly qualified investigators in accordance with Good Clinical Practice and in line with US and Tanzanian regulations. With the highest quality possible and relying on our experience and on support from the networks and DAIDS, we will screen, recruit and enroll participants; perform protocol required assignments; manage study products and dispense investigational agents as needed; monitor for, assess, and report adverse events; collect, store, process and ship specimens; collect, manage, and submit clinical research data that meet data requirements of the networks and DAIDS; conduct internal quality assurance; and create, maintain, and store research records. We will also strive to contribute to the scientific development of research priorities within the networks, and advance research and practice related to HIV/AIDS through the analyses and publication of data generated from studies that we are part.