Over the past decade, the English School of International Relations (IR) has made a remarkable resurgence. Countless articles and papers have been written on the School. Some of these works have been critical, but most have applauded the School's efforts to provide a fruitful ‘middle way’ for IR theory, one that avoids the extremes of either an unnecessarily pessimistic realism or a naively optimistic idealism. At the heart of this via media is the idea that, in many periods of history, states exist within an international society of shared rules and norms that conditions their behaviour in ways that could not be predicted by looking at material power structures alone. I f the English School (ES) is correct that states often follow these rules and norms even when their power positions and security interests dictate alternative policies, then American realist theory – a theory that focuses on power and security drives as primary causal forces in global politics – has been dealt a potentially serious blow.