Assessing an adversary’s intentions is arguably the most demanding and consequential task that national security officials and intelligence analysts face. The problem is rarely a lack of information; there is usually too much, and the challenge is to know how to filter it. Drawing on psychological and organizational theory, this masterful study shows that policymakers and intelligence analysts tend to emphasize different kinds of information in making their assessments. Political leaders are drawn to “vivid” indicators, such as face-to-face encounters and personal impressions, whereas intelligence experts rely on more concrete forms of data that can be tracked and monitored over time, such as military inventories. Yarhi-Milo explores these patterns in three rigorous case studies: British assessments of Nazi Germany’s intentions during the interwar period, U.S. perceptions of the Soviet Union during the Carter administration, and U.S. judgments about Soviet leader Mikhail Gorbachev and the Soviet Union during the last years of the Cold War. Without putting forward a definite answer, the book enriches the debate over the best way for policymakers and analysts to filter the vast pools of information they gather about rivals.