In two studies, we tested a model in which the perceived (in)compatibility of being British and Muslim (identity incompatibility) was expected to mediate between group-based discrimination and the identifications and attitudes of British Muslims. In Study 1 (N = 76), anti-Muslim discrimination was associated with lower national identification and more negative attitudes toward non-Muslims, and these relationships were mediated by perceived identity incompatibility. In Study 2 (N = 70), we additionally found that anti-Muslim discrimination predicted stronger endorsement of Islamic group rights, and this relationship was also mediated by perceived identity incompatibility. The studies highlight the importance of groupbased discrimination in shaping the perceived (in)compatibility of being British and Muslim, and, in turn, the identifications and attitudes of British Muslims.