The study will last 4 years and will comprise a one-year cross-sectional analysis and a three-year longitudinal analysis. Data will be collected from questionnaires administered during patients' routine visits to public and non-governmental organization-based HIV clinics in South Africa. In accordance with current South African national treatment guidelines, patients who have started ART will visit a clinic every 3 months during the longitudinal analysis for a total of 12 visits; patients not yet on ART will visit a clinic every 6 months for a total of 6 visits.