PURPOSE: Cardiac rehabilitation (CR) is a program of structured exercise and interventions for coronary risk factor reduction that reduces morbidity and mortality rates following a major cardiac event. Although a dose-response relationship between the number of CR sessions completed and health outcomes has been demonstrated, adherence with CR is not high. In this study, we examined associations between the number of sessions completed within CR and patient demographics, clinical characteristics, smoking status, and socioeconomic status (SES). METHODS: Multiple logistic regression and classification and regression tree (CART) modeling were used to examine associations between participant characteristics measured at CR intake and the number of sessions completed in a prospectively collected CR clinical database (n = 1658). RESULTS: Current smoking, lower SES, nonsurgical diagnosis, exerciselimiting comorbidities, and lower age independently predicted fewer sessions completed. The CART analysis illustrates how combinations of these characteristics (ie, risk profiles) predict the number of sessions completed. Those with the highest-risk profile for nonadherence (72 years old, not current smoker, higher SES, surgical diagnosis) completed 27 sessions on average. CONCLUSIONS: Younger individuals, as well as those who report smoking or economic challenges or have a nonsurgical diagnosis, may require additional support to maintain CR session attendance.