Majority-group members often hold negative attitudes toward minority-group members who identify with both the majority and their minority group. Integrating perspectives from social identity theory and acculturation research with a coalitional psychology framework, we show that an underlying mechanism for such bias is the perception that dual identifiers are disloyal to the majority group. In Study 1, majority-group participants in the U.S. questioned the loyalty of a dually identified Arab immigrant more than one who identified solely with the (American) majority group, especially under intergroup threat, which in turn predicted less favorable feelings toward the immigrant. Study 2 conceptually replicated the effect of the identity manipulation and the mediating influence of perceived loyalty on judgments about an immigrant being allowed to enlist in the U.S. military. Study 3, partially replicated the findings in Poland, focusing on Russian immigrants as targets. In Study 4, which independently manipulated both the identity expressed by immigrants and their loyalty, a dually identified immigrant whose loyalty to the majority group was portrayed as high was not judged as less qualified than an immigrant who identified only with the majority group for jobs with the potential to inflict damage on the majority group. Study 5, replicated and extended the previous studies in the context of fans of allied or rival soccer teams in Germany, revealing the moderating role of existing group relations on the hypothesized loyalty processes. In summary, coalitionally driven perceptions of (dis)loyalty appear to undergird bias toward minority-group members who hold dual identifications.