PREFACE This publication presents the results of work done for the Office of the Deputy Under Secretary of the Army for International Affairs (DUSA-IA) in FY98 anticipating the potential effects of Force XXI on multinational force compatibility in future coalition operations. This work was done in conjunction with a study examining the implications of land force dominance for U.S. Army engagement, sponsored by the Office of the U.S. Army Deputy Chief of Staff for Intelligence (DCSINT). Both studies were undertaken within RAND Arroyo Center’s Strategy, Doctrine, and Resources Program. The Arroyo Center is a federally funded research and development center sponsored by the United States Army. This work should be of interest to Army planners, as well as to students of multinational military operations and to the broader defense community. iii