A survey of NATO coordination of training programs for allied military forces and its implications about collaboration among allies in peacetime. Of the three types of training analyzed--"higher training" (co-ordination of large military formations), "unit training" of smaller teams, and specialized "individual training"--NATO authorities have achieved greatest success in "higher training." The forces of the member nations work harmoniously, and combined exercises and maneuvers have steadily increased in number and sophistication. In unit and individual training, however, NATO's role is much more limited, and the nations have preferred to retain separate programs. This lack of collaboration owes not to ineffectual NATO leadership but to NATO's legal and economic impotence and the dominance of national self-interest. Nations have found it economically disadvantageous to collectivize unit and individual training programs. NATO's experience in the training function tends to confirm the utilitarian concept of a nation's behavior in alliances. Where national self-interest is served--because of scarcity of an essential commodity or strategic necessity--cooperation is willingly engaged in. Where cooperation involves a sacrifice for the common welfare, it is declined.