The purpose of the present study was to determine the extent to which modifiable social learning constructs predicted long-term adherence to an exercise program in older individuals. Participants were 189 women aged 59 to 78 years and diagnosed with low bone density. Exercise behavior was assessed at 3-month intervals. Self-efficacy, readiness for change, orientation toward exercise, social support in general, and support specifically for exercise were measured at baseline and at 12-month follow-up. Analyses indicated that initial adoption of exercise behavior was best predicted by readiness to change. Maintenance was predicted by self-efficacy for exercise, and exercise behavior at 12 months was predicted by social support for exercise. The results were seen as supportive of the stages and processes of change model of health behavior change. Implications of the findings for interventions to enhance adoption and maintenance of exercise programs by older women are discussed.