This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. This study is a prospective longitudinal data collection for late outcomes (due to Human Immunodeficiency Virus [HIV] disease progression, treatment effects and/or an interaction of the two) and late treatment effects. The study is open to children who have participated in AIDS Clinical Trial Group (ACTG) treatment trials and infants whose mother participated in ACTG perinatal treatment trials. Data collected included history, physical exam, neurocognitive testing, clinical and laboratory evaluations, morbidity, mortality and quality of life assessments at specific intervals. This is a long-term protocol that allows us to collect clinical data indefinitely.