--- - |2 Abstract Following 9/11 and the wars in Iraq and Afghanistan, anti‐Muslim antipathy dramatically escalated in the United States. We argue that a major contributor to this hostility is endorsement of Right‐Wing Authoritarianism (RWA) because people high in RWA tend to respond aggressively toward groups that they view as threatening particularly when they perceive that such aggression is supported by authority figures. We posit that Americans high in RWA view Muslims as threatening traditional American norms and perceive that the U.S. government is at war with Islam. Across three studies, we present consistent support for our hypothesis that RWA is associated with endorsing and engaging in hostile behavior toward Muslims. In addition, this hostility is mediated by the perception that Muslims threaten societal norms and that the government is actively at war with Islam (Study 3). The implications for the reduction of aggression toward Muslims and the impact of RWA on hostility toward other outgroups are discussed. - Analyses of Social Issues and Public Policy, EarlyView.