This paper starts from the observation that, at a time when the popularity of grand theory is in decline among IR scholars, they do not agree on what they mean by theory. In fact, the celebration of theoretical pluralism is accompanied by the relative absence of a serious conversation about what 'theory' is, could, or should be. Taking the view that we need such a conversation, this puts forward the notion of 'deep theorizing'. Countering both the shallow theorizing of modern scholarship that conflates theory with scientific method, and the postmodern view that abstract narratives must be deconstructed and rejected, it offers a reading of the parameters along which substantial theorizing proceeds. Specifically, it suggests that 'deep theorizing' is the conceptual effort of explaining (inter)action by developing a reading of drives/basic motivations and the ontology of its carrier through an account of the human condition, that is, a particular account of how the subject (the political actor) is positioned in social space and time. The paper illustrates the plausibility of this metatheoretical angle in a discussion of realist, liberal and postcolonial schools of thought. This article explores practices of theorizing world politics to put forward a reading of what is called 'deep theorizing'. It starts from two observations. The first is that scholars of International Relations (IR) do not agree on what they mean by 'theory'. More than three decades after James Rosenau noted that "much of the writing [in the field] suffers from loose and ambiguous conceptions of theory" (Rosenau 1980), the editors of EJIR stated "there remains no agreement on what constitutes proper theory in IR" (Dunne et al. 2013: 14; also Burchill, 2001: 8). Instead, we are presented with different kinds and types of theories attesting pluralism not only in the sense of having an ever-growing number of theories but in the very meaning of theory (Zalewski 1996; Jorgensen 2010; Dunne et al. 2013). The second observation is that the proliferation of 'theories' goes hand in hand with the perceived decline of established 'isms'. If there is a consensus among IR scholars it seems to be dismissing 'grand theory' as suitable frameworks for generating meaningful insights and conversations This is the accepted version of a forthcoming article that will be published by Sage in European