Research suggests that members of advantaged groups who feel dehumanized by other groups respond aggressively. But little is known about how meta-dehumanization affects disadvantaged minority group members, historically the primary targets of dehumanization. We examine this important question in the context of the 2016 U.S. Republican Primaries, which have witnessed the widespread derogation and dehumanization of Mexican immigrants and Muslims. Two initial studies document that Americans blatantly dehumanize Mexican immigrants and Muslims; this dehumanization uniquely predicts support for aggressive policies proposed by Republican nominees, and dehumanization is highly associated with supporting Republican candidates (especially Donald Trump). Two further studies show that, in this climate, Latinos and Muslims in the United States feel heavily dehumanized, which predicts hostile responses including support for violent versus non-violent collective action and unwillingness to assist counterterrorism efforts. Our results extend theorizing on dehumanization, and suggest that it may have cyclical and self-fulfilling consequences.