Multilevel factors (individual and structural) influence adherence to antiretroviral therapy, particularly in high HIV prevalence areas such as South Africa. The present study examined the relative importance of structural barriers to HIV care and behavioral health factors, depression and alcohol use, in Khayelitsha, Cape Town, South Africa. People receiving HIV care in six primary care clinics in Khayelitsha (N = 194) completed the Center for Epidemiologic Studies Depression Scale, the Alcohol Use Disorders Identification Test, the Structural Barriers to Medication Taking questionnaire, and a qualitative rating of past-two-week adherence. Correlations were employed to examine associations among these variables, and hierarchical regression analysis was used to examine the unique effects of structural barriers over and above depression and alcohol use as predictors of adherence. Participants were primarily Black South African (99%) women (83%), and 41 years old on average. All four variables were significantly correlated. The hierarchical regression analysis showed that among behavioral health predictors, alcohol use alone significantly predicted ART adherence (b = -.032, p = .002). When structural barriers was added to the model, it was the only significant unique predictor of ART adherence (b = -1.58, p < .001). Findings highlight the need to consider structural vulnerabilities in HIV care in South Africa when developing behavioral health interventions.