There is limited research on booster interventions designed to maintain/improve health outcomes following cardiac rehabilitation (CR). The purpose of this study was to examine the effects of a booster intervention on health, behavioral, and clinical physical status outcomes among CR graduates randomly assigned to one of three groups: structured educational/counseling sessions by telephone ( n = 24), clinic ( n = 20), or usual care ( n = 20). The sessions were provided at 3 and 9 weeks following Phase II CR. A repeated measures experimental design was used to examine outcomes at baseline (completion of CR) and at 3 and 6 months. Although the effects of the booster interventions were not significant, there was evidence to suggest that a booster intervention, compared with usual care, had a positive effect on patients' physical functioning, adherence to the exercise program, frequency of exercise, heart rate, and blood pressure.