The purpose of this study is to characterize the quality of life (QOL) and longitudinal patterns of change in QOL outcomes in children and youth with HIV infection; to identify demographic, social, disease status, treatment, and health care utilization factors that predict longitudinal changes in outcomes; to develop a conceptual model that characterizes the effects of specific factors that predict longitudinal changes in QOL; and to characterize the influence of HIV symptoms on QOL outcomes in the domains of health perceptions, physical, psychological, and social role functioning.