['Self-efficacy is a determinant of walking performance in older adults with knee osteoarthritis. We examined whether self-efficacy mediated the effect of age, psychosocial, impairment, and mechanical factors on walking performance.', 'Fifty-four participants with knee osteoarthritis completed the Six Minute Walk test and Arthritis Self-Efficacy Scale. Independent variables reflected age, psychosocial (depressive symptoms), impairment (pain, stiffness), and mechanical (strength, obesity) factors.', 'Self-efficacy fully mediated the effect of age and impairments on walking. The effects of strength were only partially mediated by self-efficacy. Depressive symptoms and obesity were not mediated by self-efficacy.'] Does self-efficacy mediate walking performance in older adults with knee osteoarthritis?