© 2020 National Sleep Foundation Objectives: This study aimed to examine the association between sleep quality and physical performance among a group of UK community-dwelling older adults, according to sex. Methods: Sleep quality was assessed using the Pittsburgh Sleep Quality Index. Physical performance was assessed using a short physical performance battery (SPPB), a timed up-and-go, and a hand-grip strength test. Results: Of 591 eligible study members, 401 completed the Pittsburgh Sleep Quality Index. In regression analyses, men who reported poor sleep quality were significantly more likely to have a poor SPPB score, even after adjustment for confounding factors (OR = 2.54, 95% CI 1.10-5.89, P=.03). The direction of the relationship was reversed among women, where those who reported poor sleep were less likely to have a low SPPB score (OR = 0.36, 95% CI 0.15-0.85, P =.02). Poor sleep quality was associated with poorer hand-grip strength among women (regression coefficient = −0.34 z score, 95% CI −0.64, −0.04, P =.03), but this relationship was not observed among men (regression coefficient = 0.28 z score, 95% CI −0.01, 0.57, P =.06). Conclusion: We found evidence of an association between poor sleep quality and poorer physical performance in older adults, though there appear to be important sex differences.