Three studies demonstrated that a salient multicultural ideology increases hostile treatment of threatening outgroup interaction partners. The effect of multiculturalism on hostile behavior was evident regardless of whether threat was operationalized in terms of disagreement with an outgroup partner on important social issues (Studies 1 and 3) or rejection by the partner (Study 2). Moreover, the results clearly point to the learning orientation fostered by multiculturalism--as opposed to other factors such as enhanced other-focus, group-level attributions, or focus on differences--as the critical mediator of its effect on hostile behavior under threat. Thus, it appears that multiculturalism enhances the expression of hostility because it prompts individuals to really engage with and attach meaning and importance to threatening behaviors exhibited by outgroup members. The effects of multiculturalism were distinct from those of anti-racism and color-blindness, which set in motion processes that in many respects are directly opposite to those instantiated by multiculturalism. The findings highlight that the behavioral implications of multiculturalism may be quite different in conflictual interactions than they have previously been demonstrated to be in less threatening exchanges.