The International Maternal Pediatric Adolescent AIDS Clinical Trials (IMPAACT) Group is a cooperative group of institutions, investigators, and other collaborators organized for the purpose of evaluating potential therapies for HIV infection and its sequelae in the infant, pediatric, adolescent and pregnant women populations. IMPAACT was formed through a merger of investigators from the Pediatric AIDS Clinical Trials Group (PACTG) and the Perinatal Scientific Working Group of the HIV Prevention Trials Network (HPTN/HIVNET). IMPAACT is primarily funded by both the Division of AIDS (DAIDS), National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH) and the Eunice Kennedy Shriver National Institute of Child Health and Human Development (EKSNICHD), NIH. The Network also receives additional funding from the National Institute of Mental Health (NIMH), NIH.