Abstract : This report presents the results of two political-military games played at RAND in the spring of 1986 to investigate how possible European confidence- and security-building measures (CSBMs) might affect interaction between the United States and the Soviet Union in a crisis situation. The objective was to examine which of three hypotheses best describes the most likely effects of CSBMs in a crisis: (1) CSBMs can help make crucial distinctions/decisions; (2) CSBMs neither help nor harm decisionmaking; (3) CSBMs can cause more harm than good. The games provided no evidence that CSBMs could reduce the risks of miscalculation or misunderstanding. However, neither did the CSBMs appear to exacerbate misunderstandings. The players tended to focus on their own beliefs and to ignore evidence bearing on the intentions of the other side. The study indicates a need for further research on such important issues as the interplay between intimidation and surprise. Keywords: Confidence Level; Security; Crisis Management; East West Relations; Decision Making; War Games.