This study examined the effects of dietary weight loss and exercise on the health-related quality of life (HRQL) of overweight and obese, older adults with knee osteoarthritis. A total of 316 older men and women with documented evidence of knee osteoarthritis were randomly assigned to 1 of 4 18-month interventions: dietary weight loss, exercise, dietary weight loss and exercise, or healthy lifestyle control. Measures included the SF-36 Health Survey and satisfaction with body function and appearance. Results revealed that the combined diet and exercise intervention had the most consistent, positive effect on HRQL compared with the control group; however, findings were restricted to measures of physical health or psychological outcomes that are related to the physical self.