The enforcement of Arizona's new immigration law (Senate Bill 1070) requires police officers to make countless everyday judgments about whether individuals they encounter might be illegal immigrants. Understanding officers’ attitudes about immigrants, therefore, as well as the social and personal factors that influence these attitudes, will be important to predicting the consequences of enforcing this new law. Our program of research examines the role of authoritarianism, personal values, and descriptive social norms in determining attitudes about immigrants. Given the current social and political climate, as reflected in recent Arizona and national-level polls, coupled with research on psychological predispositions, our model suggests that Arizona police officers are likely to hold negative attitudes about immigrants, and that these negative attitudes may in turn influence how officers choose to enforce Senate Bill 1070 (SB 1070). To reduce improper enforcement of SB 1070, our model suggests that police training interventions would be better informed by taking into consideration (1) the general ambiguity surrounding Americans' attitudes toward immigrants, and (2) the American tradition of egalitarianism.