HIV serostatus disclosure to community members has been shown to have potential public and personal health benefits. This study examined the impact of bonding and bridging social capital (i.e. close and distant ties) on public disclosure and described the complex relationship between bonding and bridging social capital in the context of serostatus disclosure among AIDS patients enrolled in South Africa's public sector antiretroviral treatment (ART) program. Data were collected from a cohort of patients enrolled in the public sector ART program in the Free State province of South Africa. Semi-structured, face-to-face interviews were conducted with a random sample of 268 patients at three points in time (<6 months of ART, 6-12 months of ART, and 18-24 of months ART). The relationship between bonding and bridging social capital and the impact of different forms of social capital on public disclosure were determined using a fully cross-lagged regression model. The impact of bonding social capital (treatment and emotional buddy) on public disclosure was positive and invariant across time. The results from the cross-lagged regression indicated that bridging social capital (community health worker and support group) only encouraged public disclosure in the second year of treatment. At the start of treatment, bivariate analysis showed a strong negative association between bonding and bridging social capital, which diminished at follow-up and eventually disappeared in the second year of treatment. This study identified bonding social capital as a leverage to maximize potential benefits and minimize potential risks in order to shift the balance toward consistent public disclosure. Furthermore, the importance of bridging social capital initiatives is demonstrated, especially for the most vulnerable patients, those who cannot capitalize their bonding social capital by disclosing their HIV serostatus to family and friends at the start of treatment.