Adherence to HIV medication regimens is a function of multiple dimensions including psychological functioning, social support, adherence self-efficacy and optimism regarding treatment. Active substance use can also negatively affect adherence. An understanding of the nature of the associations among the correlates of adherence can better inform the design of interventions to improve adherence. This study developed an exploratory path model of schedule adherence using data from a sample 130 African-American HIV-positive crack cocaine users on highly active antiretroviral therapy (ART). This model was based on the Transactional Model of Stress and Coping developed by Lazarus and Folkman. Following the theory, the effects of psychological distress on schedule adherence were mediated by patients’ relationship with their doctor and optimism towards antiretroviral treatment. Adherence was also associated with patients’ self-efficacy regarding their medical regimen which, in turn, was associated with their social support.