'Kratochwil's book marks a major event in international relations theory. It demonstrates persuasively that it will not do to think of the international realm merely in terms of social physics, with billiard-ball states bouncing and balancing about; not merely in the instrumental rationality of the irrepressible utilitarians, who now vie for hegemony via game theory. International life, he shows, like domestic life, is constituted of rules, norms and conventions that are not epiphenomenal adjuncts of 'structures', and that give meaning both to the nature of units as well as the reasons for their actions.' John Gerard Ruggie, Colombia University