Dishman (2001) has described the need to better understand the "natural history" of exercise patterns and how they are developed and maintained. To that end, this investigation examined the level of association of stage of exercise (Transtheoretical Model) with exercise identity and exercise efficacy. Theory suggests that exercise identity and exercise efficacy should explain progression and maintenance of exercise behavior in later stages of the change process. Data were collected from 116 members of a fitness center located in a rural community in the Midwest. Ninety-three percent of the survey participants self-identified as Caucasian and 78% were female. Average age was 50.6 years with a range of 20 to 81 years. Stage of exercise behavior was assessed using a five-item instrument related to regular exercise behavior and intentions (Marcus, Selby, Niaura & Rossi, 1992). Because of cell size, precontemplation, contemplation, and preparation stages were combined. Exercise Identity was measured by the sum of nine Likert-type items (Anderson & Cychosz, 1994) designed to measure the extent to which exercise was descriptive of the concept of self (alpha=.93). Exercise efficacy (Marcus, et al., 1992) was assessed by the sum of seven Likert-type items designed to measure confidence in one's ability to overcome barriers to exercise participation (alpha=.86). A MANOVA revealed a statistically significant exercise stage effect (Wilks' Lambda=.63, F(6,212)=9.06, p<.001). Univariate results for exercise state were significant for both exercise identity, (F(2,108)=19.63, p<.001 and exercise efficacy (F(2,108)=16.08, p<.001). Age approached significance, (F(2,108)=3.05, p=.051). A stepwise regression analysis was performed with exercise stage as the dependent variable and exercise identity, exercise efficacy, and age as predictor variables. Results indicated that exercise idnetity and exercise efficacy were significantly associated with exercise stage (Rsquare=34%). Exercise identity score entered first and explained 26% of the variance in exercise stage, Exercise efficacy entered next and made a significant addition of 8%. These data provide insight into the sociopsychological process underlying maintentance and expansion of exercise activities. Data suggest that exercise identity increases through the change process, peaking in the "maintenance" stage. This is consistent with Identity Theory (Stryker & Burke, 2000) that the development of this role identity and self-perceptions of exercise efficacy may combine to sustain and perpetuate behavior. These data suggest that program efforts directed at developing these self-perceptions may be natural, perhaps even a necessary element in the process of persisting in exercise behavior.Keyword(s): adult physical activity/fitness, exercise/fitness/physical activity, health promotion