International relations theorists have in recent years shown an interest in international norms and rules not equaled since the interwar period. This contemporary literature is, of course, quite different—i.e., better—than that of the 1920s and 1930s: it has greater intellectual depth, empirical backing, and explanatory power. The promise of this research, bolstered by the opportunities of the post–cold war era, is that norms encouraging free trade, protecting the environment, enhancing human rights, and controlling the spread and use of heinous weapons may have a substantial impact on the conduct and structure of international relations. But pessimists also exist. Some have taken up the stick E. H. Carr skillfully shook at idealists in an earlier period, arguing that the anarchic power-shaped international arena is not so malleable and that international norms and institutions have relatively little influence. On the one hand, we are pointed to the centrality of international norms; on the other, we are cautioned that norms are inconsequential. How do we make sense of these divergent claims? Which is right?