We explored how political beliefs and attitudes predict support for anti‐Muslim policies and extremist behavior in the United States following the 2015 Paris terrorist attacks. A large sample completed measures of authoritarianism, social dominance orientation (SDO), generalized prejudice, identification with all humanity (IWAH), perceptions of Muslim threat, and support for anti‐Muslim policies and behaviors. These measures accounted for 73% of the variance in moderate anti‐Muslim policies and 55% of the variance in extreme anti‐Muslim policies. Authoritarianism and SDO directly and indirectly predicted support for anti‐Muslim policies, with their effects partially mediated by generalized prejudice, IWAH, and perceptions of Muslims as threatening. Threat both mediated and moderated the relationship between authoritarianism and anti‐Muslim policies. A negative interaction between authoritarianism and perceptions of Muslims as threatening predicted moderate anti‐Muslim policies, but a positive interaction predicted extreme anti‐Muslim policies. A tentative explanation is offered. Perceptions of Muslim threat was consistently a powerful predictor of anti‐Muslim policies and willingness to engage in extremist behaviors targeting Muslims. Programs to combat anti‐Muslim prejudice should consider the role of threat‐related stereotypes in expressions of anti‐Muslim prejudice.