Perceptions of economic costs and benefits play an important role in determining attitudes toward immigrants and immigration. The Unified Instrumental Model of Group Conflict, and the correlational and experimental research supporting it, indicate that when immigrants are seen as competing with members of the host society for economic resources, negative attitudes toward immigrants and immigration result. Yet measures taken to reduce this perceived competition and threat can have unforeseen consequences. Recent bills intended to reduce illegal immigration in U.S. states, such as Arizona's Senate Bill 1070 and Georgia's House Bill 87, have been framed by supporters as intended to reduce the economic costs of illegal immigration. Their consequences, however, have been increased economic hardship in the form of economic boycotts and lost farm production. We suggest that recognizing the mutual dependency between immigrants and members of host societies may be a first step in reducing support for harsh measures against illegal immigration, to the benefit of all.