Mexican immigration to the United States comprises an important social issue in contemporary public policy debate, particularly given the recent passage of Arizona's Senate Bill 1070 (SB 1070). The current study investigated how individuals’ sentiments toward undocumented Mexican immigrants shifted between 2006 and 2009 in Arizona, and also examined economic concomitants to these shifts. Participants included 3,195 culturally diverse students attending a state university in Arizona. They reported their attitudes toward undocumented Mexican immigrants regarding housing, employment, values, social welfare, citizenship, health care, and education issues. Results show less-positive attitudes as each year progressed among European and Latino Americans, as well as other ethnic minorities. Further, anti-undocumented immigrant sentiment increased as unemployment increased and gross domestic product real growth rate decreased. Ethnic differences emerged in the relative negativity toward undocumented immigrants such that European Americans were less positive towards undocumented Mexican immigrants than Latinos over 4 years. These findings suggest that economic dynamics may beget anti-immigrant sentiment, leading to contentious legislation, such as Arizona's recent immigration law.