Thirty years after the first diagnosis, people living with HIV (PLWH) around the world continue to report stigmatizing experiences. In this study, beliefs contributing to HIV-related stigma in African and Afro-Caribbean diaspora communities and their cultural context were explored through semi-structured interviews with HIV-positive (N = 42) and HIV-negative (N = 52) African, Antillean and Surinamese diaspora community members in the Netherlands. Beliefs that HIV is highly contagious, that HIV is a very severe disease, and that PLWH are personally responsible for acquiring their HIV infection were found to contribute to HIV-related stigma, as did the belief that PLWH are HIV-positive because they engaged in norm-violating behaviour such as promiscuity, commercial sex work, and, for Afro-Caribbean diaspora, also homosexuality. These beliefs were found to be exacerbated and perpetuated by cultural taboos on talking about HIV and sexuality. HIV-related stigma reduction interventions should focus on changing these beliefs and breaking cultural taboos on HIV and sexuality in a manner that is participatory and consistent with the current theory and empirical findings. Copyright © 2011 John Wiley & Sons, Ltd.