This collection of essays grapples, historically, with the complex issues involved in understanding system transformation. Often these transformations have taken the form of a shift along the spectrum of independence-centralization, and it is within the framework of such declining or emerging imperial systems that the degree of change has tended to be measured. The task of this contribution is to locate the specific case of the end of the Cold War within the broader reflections on these themes. It will respond to this challenge by applying a different litmus test for change from that already found in the existing literature about the significance of the end of the Cold War. Instead, it will broach the topic by an examination of prevailing concepts of legitimacy within international society. In short, it argues that a study of the role of legitimacy might be a useful way of documenting and measuring the kinds of changes taking place within an international system. Moreover, while the end of the Cold War might be thought to have nothing to say about the issue of empire as such (beyond recording the expiry of the Soviet version), it will additionally be suggested that the resultant extension of shared concepts of international legitimacy can be understood as a defining attribute of the contemporary imperial project.