This book and its message could not be more relevant today. After World War II, the U.S. Intelligence Community’s main objective was to understand the intentions and capabilities of the Communist threat. This meant a focus on the Soviet Union and its allies. Data on the number and capabilities of tanks, airplanes or ships in the inventory of the Warsaw Pact were not easy to come by, although somewhat easier to obtain than insight into the intentions of Communist leaders. A well-placed spy or satellite with a camera could yield some information but far from the whole picture. One of the most knowledgeable analysts who understood the importance of addressing both capabilities and intentions as a central part of the intelligence process was a woman—Cynthia Grabo. Intelligence analysis was dominated by men before, during, and after World War II. In this environment, Ms. Grabo stood out. Cynthia Grabo worked as an intelligence analyst for the U.S. government from 1942 to 1980. After graduating from the University of Chicago with undergraduate and graduate degrees, she was recruited by Army Intelligence shortly after Pearl Harbor. Although she served in various capacities during the war, from 1949 for the remainder of her career she specialized in strategic warning. Assigned to the interagency staff called the National Indications Center, she served as a senior researcher and writer for the U.S. Watch Committee throughout its existence (1950 to 1975), and for its successor organization the Strategic Warning Staff. It was during this time that Ms. Grabo recognized the need to capture the institutional memory associated with strategic warning. The viability of the U.S. intelligence system depends on analysts, collectors, humanists and technologists, all of whom must be willing in their assessments and creative work to share risks with appropriate intelligence consumers. Commanders and policymakers also promote the viability of the intelligence system if they allow analysts to fail, yet to continue their work. As Ms Grabo points out, the Intelligence Community must avoid treating the warning function as only a by-product of other intelligence production. To “work’’ a warning problem is to anticipate events in their fullest political, military, economic, diplomatic and cultural context. If the attacks on the World Trade Center and the Pentagon came as a surprise because “nothing like that had ever happened before in the U.S.,’’ then the events truly echo those of December 1941. Now, the U.S. itself is highly subject to having indications analysis practiced against it. The historical experience of the U.S. in interpreting indications of conflict, as they are brought to light in this work, can help to make us more aware of the messages we may be conveying to potential adversaries in the international environment, and therefore preserve an element of surprise for ourselves. The 21st century brings a different world in many respects, but the principles of strategic warning analysis remain the same.