This book describes how Cold War researchers used expert opinions to construct foreknowledge of geopolitical relevance. Focusing on the RAND Corporation, an American think tank with close relations to the armed forces, Dayé analyses the development of two techniques of prognosis, the Delphi technique and Political Gaming.  Based on archival research and interviews, the chapters explore the history of this series of experiments to understand how contemporary social scientists conceived of one of the core categories of the Cold War, the expert, and uncover the systematic use of expert opinions to craft prognoses. This consideration of the expert’s role in Cold War society and what that can tell us about the role of the expert today will be of interest to students and scholars across the history of science, the sociology of knowledge, future studies, the history of the Cold War, social science methodology, and social policy.