The National Institute of Child Health and Human Development (NICHD) Domestic and International Pediatric and Maternal HIV Studies Coordinating Center (?Coordinating Center?) contract provides logistical, technical, and administrative support to maintain, coordinate, and manage a multi-site network of clinical centers conducting research on treatment, prevention, diagnosis, epidemiology, and natural history of HIV infection and disease in pediatric, adolescent, and maternal patient populations. The network includes both domestic and international clinical sites. The NICHD has funded the Coordinating Center through a contract mechanism since 1987, initially for the conduct of a single clinical trial of intravenous immune globulin to prevent infections in HIV-infected children. In 1989-90, the clinical trials sites funded through the Coordinating Center began collaboration with the pediatric and adults AIDS Clinical Trials Groups funded by the National Institute of Allergy and Infectious Diseases (NIAID) for developing and conducting multiple clinical trials to treat HIV infection and its complications in children and women as well as interventions to prevent mother to child HIV transmission. This effort has successfully continued to the present. In recognition of the global nature of the pediatric and maternal HIV epidemic, the clinical trials sites funded through the contract, called the NICHD Domestic and International Pediatric and Maternal HIV Clinical Trial Network (NICHD Network), have expanded to include international clinical trials sites in Latin America and the Caribbean. The NICHD Network currently collaborates with multiple clinical trials networks, including adult and pediatric networks funded by NIAID;the Adolescent Trials Network funded by NICHD;and the Pediatric European Network for Treatment of AIDS. The Coordinating Center contract also is used to fund clinical trials that are of specific interest to NICHD and that are completely conducted and funded solely through the contract and not with other Networks. For example, the Coordinating Center contract is used to fund a study comparing different infant antiretroviral prophylaxis regimens to prevent mother to child transmission in infants born to HIV-infected mothers who have not received antiretroviral therapy during pregnancy. (For example, the mothers were not dentified as HIV-infected until they presented in labor). This trial is being conducted in the U.S., Latin America and South Africa. An operational study evaluating implementation of antenatal HIV testing and antiretroviral prophylaxis is being conducted in rural India. Additionally, in recognition of a need for further training and development to increase Latin American and Caribbean capacity for the conduct of clinical trials, particularly those involving experimental drugs, the Coordinating Center contract is funding the NICHD International Site Development Initiative (NISDI). This initiative involves the conduct of two observational studies of HIV-infected pregnant women and their infants and HIV-infected children. The studies incorporate training of international investigators in the conduct of clinical studies, regulatory requirements for such studies, and the analysis and publication of results of such studies. Finally, the Coordinating Center contract also funds and conducts cross-clinical trial analyses (meta-analysis of individual patient data) to address high priority HIV-related issues, such as risk of HIV transmission through breastfeeding. k.