This is a study of legitimacy in a global order, not legitimacy of the global order. It explores the challenging issue of what legitimacy might mean within such a context, and on what basis that order could develop its own principles of legitimacy. Its purpose is to garner further insights into the nature of contemporary global governance, and resistance to it, inasmuch as the latter is widely deemed to be symptomatic of the legitimacy crisis at its heart. A multitude of writers, working from quite different perspectives, is in agreement that it is this lack of legitimacy that threatens the very fabric of the order. Indeed, it is common to regard the emergence of concerns about the declining legitimacy of any system as itself indicative of some kind of failure within it: the concept tends to be associated with the ‘politics of crisis’. Accordingly, we are most likely to ask questions about the legitimacy of a system only when things appear to be going wrong. If this is so, legitimacy provides a vital key to understanding the tensions within the contemporary global order.