In the Anglosphere, most undergraduate introductory courses for International Relations (IR) still begin with an overview of the canonical ‘forefathers’ of realism, and their ‘great debate’ with idealism. Students cannot escape the ‘classical’ realism, presented as a homogeneous tradition, and its famous realists: often a combination of Hans Morgenthau, Arnold Wolfers, Reinhold Niebuhr and E. H. Carr. Realism in IR, however, has never been homogeneous, and the reductionist stratification of IR theory into rigid factions is becoming increasingly contested. In recent years, new generations of IR scholars have led a growing introspection into the underlying assumptions of the field and its history, which has fostered critical approaches to IR's historical sociology. It is in this vein that Haro Karkour has undertaken a comprehensive reassessment of E. H. Carr's place within the discipline of IR. Aside from being a forefather of the classical realist canon, Carr was known for his histories of the Soviet Union and his lectures on historiographical methodology. What does Marxist historian Carr have in common with the realist school of thought that houses neo-realists like John Mearsheimer? According to Karkour's reassessment of Carr's legacy, the answer is more complex than IR scholars have been led to believe.