How do policymakers infer the long-term political intentions of their states' adversaries? A new approach to answering this question, the “selective attention thesis,” posits that individual perceptual biases and organizational interests and practices influence which types of indicators a state's political leaders and its intelligence community regard as credible signals of an adversary's intentions. Policymakers often base their interpretations on their own theories, expectations, and needs, sometimes ignoring costly signals and paying more attention to information that, though less costly, is more vivid (i.e., personalized and emotionally involving). In contrast, intelligence organizations typically prioritize the collection and analysis of data on the adversary's military inventory. Over time, these organizations develop substantial knowledge on these material indicators that they then use to make predictions about an adversary's intentions. An examination of three cases based on 30,000 archival documents and intelligence reports shows strong support for the selective attention thesis and mixed support for two other approaches in international relations theory aimed at understanding how observers are likely to infer adversaries' political intentions: the behavior thesis and the capabilities thesis. The three cases are assessments by President Jimmy Carter and officials in his administration of Soviet intentions during the collapse of détente; assessments by President Ronald Reagan and administration officials of Soviet intentions during the end of the Cold War; and British assessments of Nazi Germany before World War II.