Little is known about the clinical picture of cocaine users presenting with chest pain in the ED from the substance abuse or health services perspective. Almost all of the research on cocaine users presenting to the ED with chest pain has been conducted from the perspective of the ED physician and hence has focused on cardiac outcomes and mortality. Before we can develop interventions for this high-risk group of cocaine users, we need to understand who is at greatest risk for poor outcome and who is least likely to enter treatment in order to target interventions for those most in need. Likewise, we need to know where and when high-risk individuals intersect with the health care system to determine the optimal timing and setting for interventions. We propose a prospective observational study to provide the foundation for subsequent intervention research. We propose to study a consecutive cohort (N=300) of individuals presenting to the Hurley Medical Center ED, Flint, MI with chest pain and recent cocaine use and to follow them longitudinally for a year after their ED presentation with interviews at 3, 6, and 12 months. The specific aims of the study are: (1) To develop a comprehensive portrait of a consecutive cohort of cocaine users presenting to the ED with chest pain; (2) To identify specific locations where study participants interact with the health service system in the year following their ED visit and to identify the key patient characteristics associated with types of service use; (3) To identify access barriers to engaging in treatment and use of other services including primary care; (4) To measure one-year outcomes for this Cohort and to identify key socio-demographic and clinical characteristics of cocaine-using individuals with poor or good outcomes in the year after their ED visit for chest pain; and (5) To identify the timing and service setting for future interventions, based on findings from Specific Aims 1-4. The proposed study will study barriers to obtaining treatment, including access (multi-dimensional measures including accessibility, availability, acceptability, and affordability of treatment services), motivation (readiness to change), and need for treatment, including severity of cocaine dependence, comorbid conditions including other substance dependence, and comorbid medical conditions. Therefore, this proposed longitudinal observational study will identify key observational data and directions for future work to develop interventions in the ED or elsewhere to enhance treatment engagement, linkages to primary care, and changes in drug use for this understudied population already experiencing potentially harmful medical consequences of their drug use.