Three experiments tested hypotheses about why humor that disparages some groups fosters discrimination whereas humor that disparages others does not. Experiment 1 showed that disparagement humor fosters discrimination against groups for whom society’s attitudes are ambivalent. Participants higher in anti-Muslim prejudice tolerated discrimination against a Muslim person more after reading anti-Muslim jokes than after reading anti-Muslim statements or neutral jokes. Experiments 2 and 3 tested the hypothesis that disparagement humor promotes discrimination against groups for whom society’s attitudes are ambivalent but not groups for whom prejudice is justified. In Experiment 2 participants higher in anti-Muslim prejudice discriminated against Muslims more after reading anti-Muslim jokes than neutral jokes, while antiterrorist jokes did not promote discrimination against terrorists. In Experiment 3 participants higher in antigay prejudice discriminated against a gay student organization more after reading antigay jokes than after reading neutral or antiracist jokes; antiracist jokes did not promote discrimination against a racist student organization.