 Study visits will occur at study entry; Weeks 1, 2, 4, 8, 16, and 24; and every 12 weeks thereafter. A physical exam, blood collection, and urine collection will occur at most visits. Two pharmacokinetic blood samples will be collected from participants between Weeks 4 and 24. Participants will undergo adherence training at study entry and will be asked to complete adherence questionnaires at selected study visits. Some participants will be asked to participate in ACTG A5224s, a metabolic substudy of ACTG A5202. 