Within the physical activity domain the majority of transtheoretical model research has employed a cross-sectional research design. While useful for characterizing participants within the various stages of change, it fails to capture the dynamic nature of change. This study`s purpose was to identify predictors of naturally occurring transitional shift patterns in physical activity behavior observed over 6 months among 98 college students. The full set of variables from the transtheoretical model as well as exercise METS were examined. Using multinomial logistic regression analysis, stable active participants reported more exercise METs at baseline than both activity adopters and perpetual preparers (p<.01). Stable active participants were also significantly different in their cognitive process of change scores compared to activity adopters (p<.05). Activity adopters differed from stable active participants in their initial decisional balance scores (p<.05). These findings should help inform theory development and physical activity interventions and programs.