Adherence to antiretroviral medications is central to reducing morbidity and mortality among people living with HIV/AIDS. Relatively few studies published to date address HIV adherence among special populations. The purpose of this article is to review the existing literature on HIV antiretroviral adherence, with an emphasis on studies among the triply diagnosed population of people living with HIV/AIDS, mental illness, and chemical dependency. In order to reflect the most current information available, data from conference proceedings, federally funded studies in progress, and the academic literature are presented for consideration.