This review critically examines Transtheoretical Model (TTM)-based interventions for physical activity (PA) behavior change. It has been suggested that the TTM may not be the most appropriate theoretical model for applications to PA behavior change. However, previous reviews have paid little or no attention to how accurately each intervention represents the TTM. Findings comprise two sections: sample characteristics of each intervention reviewed and a summary outlining the use of the TTM to develop the interventions. Results reveal numerous inconsistencies regarding the development and implementation/application of TTM-based interventions. Specifically, the majority of interventions reported to be based on the TTM fail to accurately represent all dimensions of the model. Therefore, until interventions are developed to accurately represent the TTM, the efficacy of these approaches and the appropriateness of the underpinning theoretical model cannot be determined. (Contains 1 figure, 3 tables, and 1 note.)