Objective: In this secondary analysis of data from the OPTICARE trial, we compared the effects of two behavioral interventions integrated into cardiac rehabilitation to standard rehabilitation with regard to functional capacity, fatigue, and participation in society. Design: This is a randomized controlled trial. Setting: This study was conducted in a cardiac rehabilitation setting. Subjects: A total of 740 patients with acute coronary syndrome were recruited for this study. Interventions: Patients were randomized to (1) three months of standard rehabilitation; (2) cardiac rehabilitation plus nine months after-care with face-to-face group lifestyle counseling; or (3) cardiac rehabilitation plus nine months after-care with individual lifestyle telephone counseling. Main measures: Functional capacity (6-minute walk test), fatigue (Fatigue Severity Scale), and participation in society (Utrecht Scale for Evaluation of Rehabilitation-Participation) were measured at randomization, 3, 12, and 18 months. Results: Additional face-to-face sessions resulted at 12 months in 12.49 m more on the 6-minute walk test compared to standard rehabilitation (P =.041). This difference was no longer present at 18 months. Prevalence of fatigue decreased from 30.2% at baseline to 11.9% at 18 months compared to an improvement from 37.3% to 24.9% after standard rehabilitation (between-group difference: odds ratio = 0.47; P =.010). The additional improvements in functional capacity seemed to be mediated by increases in daily physical activity. No mediating effects were found for fatigue. No additional improvements were seen for participation in society. Additional telephonic sessions did not result in additional intervention effects. Conclusion: Extending cardiac rehabilitation with a face-to-face behavioral intervention resulted in additional long-term improvements in fatigue and small improvements in functional capacity up to 12 months. A telephonic behavioral intervention provided no additional benefits.