It is now more than twenty years since Jürgen Habermas's work was first referred to in International Relations (IR) theory. Along with many other continental philosophers and social theorists, Habermas was initially mobilised in the critique of positivism, and in particular neorealism, in IR theory. As such, the interest in Habermas and IR must be located in the first instance within the context of the fourth debate. This Forum section of the Review provides us with the opportunity to take stock and ask whether the dialogue between Habermas and IR has, thus far, been useful in providing new conceptual and methodological tools to analyse international politics and in inspiring new research agendas in IR. We also ask whether the role that dialogue plays within Habermas's work has been useful in formulating a critical theory of international relations.