Although exercise is beneficial in the older population, leisure physical activity tends to decline with advancing age. Knowledge, attitudes, intentions, expected benefits, beliefs about personal control of health and fitness, perceived barriers to physical activity, and self-efficacy have been associated with participation in physical activity among young and middle-aged adults. These factors and interventions for increasing physical activity have not been well studied in persons aged 65 years or older. Methods to standardize research in this area and combine data with clinical observation are needed to achieve the physical activity objectives set for older adults for the year 2000.