Dramatic reductions in HIV mortality and morbidity have followed the widespread use of potent combination antiretroviral (ARV) medication regimens. Yet, the potential of the combination therapies can be realized only if people living with HIV adhere to the difficult treatment regimens. Maximizing adherence and achieving the full potential of the antiretroviral therapies demand multidimensional initiatives that address complex behavioral and biomedical issues. This prospective, randomized controlled trial will test the effectiveness of an intervention that is drawn from a self-regulation model. Self-regulation theory emphasizes the importance of patients' perceptions about their illness and treatment and provides a useful framework for broadening a patient-centered understanding of the dynamic factors involved in ARV medication adherence behavior. The primary aims of this study are: (1) To determine if the theory- based ARV intervention increases adherence, and; (2) To determine if the intervention improves health outcomes (virologic, immunologic, clinical events, QOL). Secondary aims are: (1) To determine if HIV illness representation is changed as a result of the intervention; (2) To determine if HIV illness representation predicts ARV adherence; (3) To determine if the effect of the intervention on ARV adherence and health outcomes is mediated by HIV illness representation, and; (3) To provide an analysis of the cost of the intervention. The intervention will be tested in a diverse community-based sample of 200 individuals who are receiving medications through the Ohio Department of Health HIV/AIDS Drug Assistance Program (ADAP). The focus of this intervention is on understanding the patient's HIV illness representation and: (1) providing a core of information, skills and affective support to promote a representation consistent with ARV adherence, and; (2) addressing existing perceptions within the HIV patient's illness representation that are inconsistent with ARV adherence. The intervention will be delivered by trained registered nurses with expertise in HIV care via scheduled telephone sessions (weeks 1, 2, 3, 4, 6, 8, 10, 12, 16, 20, 24, 28, 32, 36) and consultation (16 hr/day pager access). Measures will be taken at baseline and 1, 3, 6, 9 and 12 months. The duration of project data collection is 3 years. Findings will have implications for theory development, HIV clinical practice and policy.