Poor physical function status in elders is a robust predictor of not only medical service use and institutionalization but also mortality. We assessed whether depressive symptoms and low social support would predict deficits in three domains of physical function among 3,240 community-dwelling older adults in the Piedmont of North Carolina over one year. Between 7-23% of the sample declined in functional ability, depending on the domain tested. Depressive symptoms and receipt of instrumental support predicted declines in all domains of physical function. Giving instrumental support and subjective social support protected elders against declines, and subjective social support buffered the detrimental effect of depression on risk of physical decline. This study suggests that significant risk of functional impairment could be reduced among elderly persons if coincidental depressive symptoms could be alleviated and/or deficits in their social environment remedied.