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. The advent of potent ART has resulted in the survival into adolescence of an increasing proportion of infants and children with perinatal HIV infection. At the same time, the number of newly HIV-infected infants in the U.S. has decreased dramatically since 1993 with the development of effective means to prevent mother-to child transmission of HIV. Thus, the largest group of children with perinatal HIV infection in the U.S. consists of pre- adolescents and adolescents. Some of these children represent long-term slow-progressors, while others have benefited from potent combination ART. The impact of HIV infection and its treatment on the growth and development of this cohort of children who have been living with HIV infection since birth is not fully known. The PHACS AMP protocol is designed to study the effect of HIV infection on key processes of maturation such as pubertal development, bone growth, fat distribution, and hepatic, renal and cardiovascular functions. In addition, behavior in adolescents plays a major role in adherence to medications, treatment failure, evolution of viral resistance, and secondary transmission of HIV, including the transmission of resistant virus, to others. This knowledge can form the basis for interventions to improve the quality of life of infected children. Unfortunately, the number of HIV-infected infants, children and adolescents worldwide is growing substantially in both resource-poor countries and in countries with increasing levels of health care. Thus the information gained from this study will benefit the increasing number of infected youth worldwide.