This is a multi-method, longitudinal design research study. Subjects must be enrolled in ATN 125 at the time of the ATN 135 baseline visit. There will be no randomization procedures. During the 39-week study, surveys will be administered to adolescents and young adults transitioning to adult care via Audio Computer Assisted Self Interviews (ACASIs), which will collect data on individual (e.g., psychosocial and behavioral) and clinical factors affecting transition at 0 and 39 weeks. Demographic, biomedical, antiretroviral therapy (ART) and healthcare utilization visit information collected through ATN 125 medical chart abstraction will also become part of the ATN 135 subject dataset. One-time phone surveys and interviews with AMTU and adult clinic staff will also be conducted to collect information on transition protocols as well as review of any documentation of existing transition protocols (e.g., transitioning SOP). Outcome measures will include pre- and post-transition VL and other measures of physical and psychosocial health status to compare individuals with different patterns and outcomes of transition.