Group Empathy Theory posits empathy felt by members of one group can boost support for another even when the groups are in direct competition for rights, security, and resources. We employ our theory to explain divergent reactions of majority versus minority groups to immigration threats. We conduct a two-wave national survey experiment with 1,799 participants consisting of a randomized sample of Anglos and randomized, stratified oversamples of African Americans and Latinos. The experiment manipulates racial/ethnic cues in a vignette depicting an ambiguous yet potentially threatening incident at an immigrant detention center. African Americans and Latinos are significantly more likely to side with minority detainees and support pro-civil rights policies and actions. The theory’s presumed causal mechanism—group empathy—is substantially stronger among African Americans and Latinos, and has a significant mediating effect on such distinct reactions.