A developed-world consensus ties state failure to new and serious international insecurity. But that conclusion rests upon an uncertain foundation; insights into the nature and intensity of failure-related threats remain tentative and unsystematic. This study begins to remedy the problem, examining the broad relationships between weakness, failure, and terrorism with panel data for 153 countries (1999–2008). I argue that the quantitative literature too often disregards the political context determining terrorism's use, that terrorism is endogenous to many measures of state failure, and that estimates of the failure-related threat of terrorism are overstated. Consistent with these expectations, I find that most failing and failed states are not predisposed to terrorism. However, among the "most failed" states, those at war or experiencing political collapse are significantly more likely to experience and produce terror. These results refine the relationship between failure and external threat and highlight the importance of terrorism's macro-level political context.