This study examined the moderating effects of social support in a fall prevention program for community-dwelling older adults. Twenty-six Japanese older adults age 65 and older participated in a 2-month exercise program and were measured in anthropometrical, physical, and psychological functioning at baseline, 2 months (intervention termination), and 5 months (3 months after intervention termination). Analyses indicated that the program did not improve participants' body mass index, balance, or walking speed. However, participants'falls self-efficacy significantly increased from baseline to intervention termination and was maintained at a higher level at the 5-month postintervention follow up. This efficacy-improving effect was prominent in the participants who had received less social support at baseline. The findings emphasized the importance of considering participants' social resources and targeted intervention outcomes when evaluating the effect of exercise.