The debate about the purpose (and uses) of studying diplomatic and international history are as old as the subject itself. This article traces the origins and development of diplomatic history as a specialized field within history as a wider discipline, before exploring more recent challenges to it. The article seeks to highlight both the scope for, and the opportunities to be found in, cross‐fertilization with ideas derived from cognate disciplines. At the same time, it also seeks to show the conceptual and methodological pitfalls of recent attempts at innovation in the field. It concludes by reasserting the essential importance of politics as the core of international history and by underlining its potential for guiding current policy as well as its limitations in that respect.