The reaction of Americans to the terrorist attacks of September 11, 2001, has been massively disproportionate to the actual threat posed by al-Qaida either as an international menace or as an inspiration or model for homegrown amateurs. An examination of the activities of international and domestic terrorist “adversaries” reveals that exaggerations and distortions of the threat have inspired a determined and expensive quest to ferret out, and even to create, the nearly nonexistent. The result has been an ill-conceived and remarkably unreflective effort to react to an event that, however tragic and dramatic in the first instance, should have been seen to be of only limited significance at least after a few years. Not only has the terrorism delusion had significant costs, but the initial alarmed perspective has been so internalized that anxieties about terrorism have persisted for more than a decade despite exceedingly limited evidence that much fear is justified.