The authors proposed to (a) determine the influence of phase II cardiac rehabilitation (CR) on task and barrier efficacy and mood in men and women, (b) determine the influence of task and barrier efficacy on postphase II CR exercise adherence, and (c) examine the bidirectional relationship between self-efficacy and mood. Fifty-seven men and 24 women completed task and barrier efficacy scales and the anxiety, depression, and vigor subscales 3 to 5 weeks before phase II CR, immediately before and after phase II CR, and 6 to 10 weeks after phase II CR. They found that the women had significantly larger increases in task and barrier efficacy from pre- to postphase II CR than the men did, whereas both men and women had a significant decline at follow-up. Men and women had a similar decrease in anxiety and an increase in vigor during phase II CR. However, vigor significantly declined at follow-up. All changes in mood were significantly related to changes in task and barrier efficacy.