Interventions to reduce car use have shown limited success, in part due to limitations in models of transport choices. The theory of planned behavior (TPB) has provided a useful predictive model of car use but the specific beliefs that underpin TPB-specified cognitions are less well understood. In this study, 229 university employees responded to a questionnaire and then reported their commuting choices 1 week later. Intention and perceived behavioral control (PBC) predicted car use (R2 = .79). Intention was predicted by attitude, subjective norm, PBC, and moral norm (R2 = .56). Beliefs could not be differentiated into attitudinal and PBC constructs, but seven beliefs predicted TPB cognitions. A similar model was tested for public transport use. The results identify key targets for future interventions.