We investigated the effect of early antiretroviral treatment (ART) initiation on HIV status disclosure and social support in a cluster-randomized, treatment-as-prevention (TasP) trial in rural South Africa. Individuals identified HIV-positive after home-based testing were referred to trial clinics where they were invited to initiate ART immediately irrespective of CD4 count (intervention arm) or following national guidelines (control arm). We used Poisson mixed effects models to assess the independent effects of (a) time since baseline clinical visit, (b) trial arm, and (c) ART initiation on HIV disclosure (n = 182) and social support (n = 152) among participants with a CD4 count > 500 cells/mm3 at baseline. Disclosure and social support...