INTRODUCTION: Osteoarthritis (OA) is one of the leading causes of chronic disability in older adults, often causing significant impairment of mobility. OA symptoms have been linked to mental functioning, including depression, anxiety, and negative affect. METHOD: To examine whether anger and anxiety mediate the relationship between social support and mobility among older adults with knee osteoarthritis, data from the Everyday Quality of Life in Older Blacks and Whites with Osteoarthritis (EQUAL) study ( RESULTS: While univariate models for both anxiety and anger were significant, only anxiety mediated the relationship between social support and mobility. CONCLUSION: Although limited by their cross-sectional nature, the findings suggest that at least part of the association of social support with mobility may be explained by the role of support in alleviating anxiety.