The aims of the present study are fourfold: to apply the theory of planned behavior (TPB) to eating a low-fat diet; to consider differences between self-efficacy and perceived control over behavior (PCB); to examine self-identity as a potential addition to the model; and to identify beliefs which may provide useful targets for interventions. Findings support the efficacy of the TPB as a predictor of low-fat diet. Evidence for the distinction between self-efficacy and PCB was provided by principal components analysis, patterns in prediction of intention, and the control beliefs associated with the two constructs. Self-identity was found to independently predict intention and may prove a useful addition to the TPB. Finally, specific beliefs distinguished intenders from nonintenders, providing potential targets for health interventions. The findings are discussed in the context of previous TPB research and the need for multimethod assessments of behavior.