An integrative model of readiness to exercise (Marcus, Eaton, Rossi, & Harlow, 1994) was tested. Measures of stage of exercise adoption and of the 2 motivation variables from the model plus 3 others were obtained at baseline and 6 months later from 238 young adult females. Logistic regression analysis was used to assess the effects of both state (baseline) and change measures of the variables on progressive and regressive movement among the stages of change. Progression was predicted by change in self-efficacy (p= .018), change in perceived behavioral control (p= .007), and a baseline measure of desire to exercise (.041). Regression was predicted by change in self-efficacy (p= .04). These findings provide only partial support for the integrative model.