The importance of community support when scaling-up antiretroviral treatment (ART) in resource-limited settings is poorly understood. We assessed the impact of baseline health, patient characteristics and community support on ART outcomes at 6 and 12 months in a representative sample of 268 patients enrolled in the Free State public sector ART program (South Africa). Delayed ART initiation reduced ART response, whereas support from treatment buddies, community health workers and support groups significantly improved treatment outcomes.