Role-identities are integral parts of the concept of self. Sociological traditions suggest that they serve to give meaning and importance to past behavior as well as providing direction for future behavior. This investigation examined the relationship of Exercise Identity with: age of subject, three measures of exercise commitment, and three physiological indicators of fit­ness. Data were collected from 448 of the 531 (84%) law enforcement personnel of a state department of public safety during annual physical exams at the university fitness clinic. Ninety-eight percent of the subjects self-identified as Caucasian and 96% were male (mean age = 39, range 21-63). Exercise Identity was measured by the sum of nine Likert-scaled items designed to measure the extent to which exercise was descriptive of their concept of self ( a. = .94). Stepwise regression analysis indicated that the behav­ioral measures ( minutes per week of exercise, number of weeks of exercising, and level of perceived exertion) and physiological indicators (muscular endurance, percent body fat, and V02PEAK all standardized for age and gender) and age were significantly associ­ated with Exercise Identity (overall R2 = .54). The contribution of total cholesterol/VHDL ratio was non-significant. This evidence supports the theory of reciprocal determinism between exercise behavior and Exercise Identity, while suggesting the possibility of an identity-reinforcing role for physical fitness. These data provide insight into the sociopsychological process underlying maintenance and expansion of exercise activities.