One of the central pillars of US counterterrorism policy is that capturing or killing a terrorist group's leader is effective. Yet this pillar rests more on a foundation of faith than facts. In Leadership Decapitation, Jenna Jordan examines over a thousand instances of leadership targeting--involving groups such as Hamas, al Qaeda, Shining Path, and ISIS--to identify the successes, failures, and unintended consequences of this strategy. As Jordan demonstrates, group infrastructure, ideology, and popular support all play a role in determining how and why leadership decapitation succeeds or fails. Taking heed of these conditions is essential to an effective counterterrorism policy going forward.