International relations theorists are increasingly turning to historical sociology as a means both of broadening and refining their discipline, and critiquing mainstream thinking. Nevertheless, there is still only a rudimentary understanding of what historical sociology is and what it can offer the subject. This book acts as a manifesto for historical sociology, considering a range of issues, including accounts of the major variants of historical sociology; how they can be applied to international relations; why international relations theorists should engage with these approaches; and how historical sociological insight can enhance and reconfigure the study of international relations. In addition to describing the seven major approaches - neo-Weberianism, constructivisim, critical historical materialism, critical theory, postmodernism, structural realism and World Systems theory - the volume's introductory and concluding chapters set out in detail an approach and research agenda that revolve around what the editors call 'world sociology'.