Purpose.Goal setting is an established strategy in health behavior change programs although its usefulness remains uncertain. The authors investigate the validity of attainment of a patient-identified goal as an outcome measure in cardiac rehabilitation after myocardial infarction.Methods.On entry into a randomized controlled trial of cardiac rehabilitation after an acute myocardial infarction, patients identified one activity that, if and when attained, would reflect their perception of a successful recovery. Patients reported whether they had attained their goal and the time of goal attainment. This was then related to trial outcomes that included generic and specific health-related quality of life and percent predicted exercise tolerance.Results.Goals identified by 180 of the 201 (89.6%) patients, were attained by 51.5% at 8 weeks and by 86.5% at 12 months. At the end of the 8-week intervention, there was a substantial trend for fewer rehabilitation than usual care patients to have attained their identified goal (P < 0.06), although rehabilitation patients demonstrated greater improvement in specific health-related quality of life and exercise tolerance than usual care patients (P < 0.05). Among patients who identified a recreational physical activity goal (26.7%), significantly fewer (P < 0.007) rehabilitation than usual care patients had attained their goal at the end of the intervention with no differences in improvement in outcomes.Conclusions.Although improvement in outcomes was greater in rehabilitation patients than usual care patients at 8 weeks, goal attainment, particularly for the recreational physical activity goal, was greater among usual care patients. The validity of self-identified activity goal attainment as a measure of the efficacy of cardiac rehabilitation is unclear and might give misleading results.