It is now more than three decades since various post-positivist approaches were introduced into the discipline of International Relations (IR) by scholars launching ‘massive attacks’ on positivism. However, many continue to express concern about the ‘marginalization’ of post-positivist scholarship within IR, while others discuss how and why ‘theoretical proliferation’ has come about in the field, convinced that IR is ‘a plural, and pluralist, field.’ Neither group, however, offers the empirical evidence needed to sustain its argument. To provide such evidence, this article undertakes an empirical investigation of the extent to which post- positivist research is practised in contemporary IR, examining publishing and teaching practices in American IR, and the rapidly emerging Chinese IR community. The findings of this investigation will be useful in broadening the debate about theoretical diversity in the discipline.