Why did the United States and Iraq find themselves in full-scale conflict with each other in 1990–91 and 2003, and in almost constant low-level hostilities during the years in-between? The situation was neither inevitable nor one that either side, in full possession of all the relevant information about the other, would have purposely engineered: in short, a classic instance of chronic misperception. A combination of the psychological literature on perception and its pathologies with the almost unique firsthand access of one of the authors to the decisionmakers on both sides—the former deputy head of the United Nations weapons of mass destruction inspection mission in the 1990s, the author of the definitive postwar account of Iraqi WMD programs for which he and his team debriefed the top regime leadership, and a Washington insider in regular contact with all major foreign policy agencies of the U.S. government—reveals the perceptions the United States and Iraq held of each other, as well as the biases, mistakes, and intelligence failures of which these images were, at different points in time, both cause and effect.