Self-efficacy (SE) for overcoming barriers to exercise is key to continued exercise behavior in cardiac rehabilitation (CR). This study examined factors influencing patients' SE for overcoming barriers to exercise in CR. It was hypothesized that stress after a cardiac event would have a negative impact on SE, but that social support would be related to less stress and more SE. Measures of SE for overcoming barriers to exercise in CR, perceived stress, general forms of social support, and sources of support for exercise were completed by 459 men and 138 women upon entry into CR. Structural equation modeling revealed that general support was related to less stress and more support for exercise, which were both related to increased SE.