In this paper, we contrast the value-belief-norm (VBN) model and the theory of planned behavior (TPB) for the first time regarding their ability to explain conservation behavior. The participants represent a convenience sample of 468 university students. Using survey data and adopting previously established compound measures, structural equation analyses revealed a remarkable explanatory power for both theories: TPB's intention accounted for 95% of people's conservation behavior and VBN's personal norms accounted for 64%. Compared to the VBN model, the TPB covered its concepts more fully in terms of proportions of explained variance. More importantly, the fit statistics revealed that only the TPB depicts the relations among its concepts appropriately, whereas the VBN model does not.