Public reporting programs such as the “See Something, Say Something” campaign are important counterterrorism measures. Yet public knowledge about terrorism is low, and Americans tend to associate terrorist activity with Muslims and Middle Easterners rather than with Whites. The consequence may be biases in public reporting that lead to discriminatory law enforcement. Using data from a national survey experiment (n = 700), we examine how suspect ethnicity, ethnic stereotypes, and national identity intersect to affect willingness to report terrorism-related behaviors to the police. Our results reveal that reporting is not based on suspect ethnicity alone (White vs. Muslim Middle Eastern). Rather, the relationship between willingness to report and suspect ethnicity is conditional on endorsement of Muslim stereotypes and national identity. Our analyses also identify key antecedents of terrorism reporting, including strength of national identity, perceived procedural justice, and anger about terrorism. We conclude by offering recommendations for increasing the effectiveness of public reporting programs.