This study examined longitudinal differences in use of transtheoretical model (TTM) behavior change constructs in maintainers (who reached and maintained exercise guidelines), relapsers (who reached guidelines, then regressed), and nonchangers (who did not reach guidelines). Data from two population-based TTM-tailored randomized trial intervention groups targeting exercise behavior (N = 1050) were pooled, and analyses assessed differences in TTM constructs between the three groups at baseline, 12 months, and 24 months. Findings indicated that relapsers tended to use TTM variables similarly to maintainers with the exception of self-efficacy, consciousness raising, and most behavioral processes of change, at 24 months. Nonchangers, however, used all TTM variables less than maintainers at nearly every time point. Findings suggest that relapsers remain more active than nonchangers in terms of use of change processes. Poor response to interventions (nonchangers) may be predicted by low baseline engagement in change processes. Although relapsers reverted to physical inactivity, their overall greater use of TTM constructs suggests that their efforts to change remain better than those of the stable nonchanger group. Future research can focus on treatment engagement strategies to help the stable nonchangers initiate change and to help relapsers to maintain treatment gains.