This study examined whether psychological, physiological, and health and lifestyle measures were associated with adherence to a structured exercise program for older women. Women aged "60 to 85 years (N = 102)," randomly recruited from the community, were assessed on these measures before and after a 12-month exercise trial. Sixty-nine women completed the trial, and 54 continued participation after the trial for at least 6 months. Adherence was examined at various stages during the trial. Multiple regression analysis revealed that reduced muscle strength, slow reaction time, and psychoactive drug use explained most of the variance in adherence during the trial. In contrast, muscle strength, reasoning ability, depression, and self-reported improvement in strength best predicted continued participation after the trial. The findings have implications for community-based exercise programs and research trials.