--- - |2+ Objective Why are some terrorist attacks so much more devastating than others? Despite the importance of this question, few studies examine the great variance in lethality across terrorist incidents. This article proposes that some cultures witness deadlier terrorism. In particular, it maintains that deadlier terrorism will occur in cultures of honor that socialize individuals to view violence as an acceptable means for upholding a reputation for toughness. Cultures of honor produce terrorists motivated by perceived slight and reputational challenges, which they are compelled to rectify through especially severe acts of violence. Reclaiming one's honor is possible by inflicting maximum damage on the offending person or group. Method This argument is empirically tested in a multilevel statistical analysis of domestic terrorism in the United States from 1970 to 2015. Results Clear evidence emerges that terrorism is deadlier in the U.S. South—the quintessential culture of honor—than in the other regions of the United States. Other variables highlighted in the existing literature, however, receive mixed support. Conclusion The evidence presented in this article indicates that cultural variables help explain variation in terrorist attack lethality. Future research on political violence, including terrorism, would benefit from taking culture into greater consideration. - 'Social Science Quarterly, EarlyView. '