Project Summary The Strategic Timing of Antiretroviral Treatment (START) is an international randomized trial designed to determine whether initiation of ART at CD4+ counts > 500 cells/mm3 (immediate or early ART) is superior in terms of morbidity and mortality to deferral of ART until the CD4+ declines to 350 cells/mm3 (deferred ART). On May 15, 2015 after an average of 3 years of follow-up, the independent Data and Safety Monitoring Board (DSMB) for START determined that the study primary question had been answered. Over an average follow-up of 3 years, immediate use of ART provided significant benefit over deferred ART for the primary endpoint (a composite of AIDS and non-AIDS events) of START (rates were 0.60 and 1.38 per 100 person years for the immediate and deferred ART groups. The DSMB recommended that results be immediately disseminated, that participants in the deferred ART group be offered ART, and recognizing the relatively short follow-up, that follow-up continue. With this proposal, investigators in the International Network for Strategic Initiatives in Global HIV Trials (INSIGHT) will continue follow-up of the 4,684 HIV-positive participants enrolled in START through December 2021, and carry out final data analyses aimed at determining whether the risk of major morbidity and mortality associated with delayed initiation is eliminated once ART is initiated and HIV RNA levels are suppressed or whether it persists. No prior randomized trial has addressed this question. Multiple papers will summarize the long-term follow-up findings and results will also be presented at scientific conferences.