Modes of dialectical reasoning were introduced into International Relations (IR) from the 1980s onwards in the context of the post-positivist debate as an alternative intellectual resource drawn from the philosophy of the social sciences. To the extent that the deployment of dialectics for IR drew upon Marx and the wider Hegelian Marxist tradition, it was challenged philosophically and substantively on two fronts. Philosophically, the problem emerged how to disassociate dialectics from the ‘systemic’ Hegelian legacy, which expressed itself in the naturalism and monism of dialectical materialism, and how to overcome a reading of capital as a self-unfolding conceptual category, expressed in systematic dialectics, which de-historicised and de-subjectified capitalism as a social relation. Substantively, the problem remained how to anchor a Historical Sociology of international relations in a historicist philosophy of praxis to avoid the temptation of a relapse into structuralist modes of explanation. By addressing this double challenge, this paper identifies a central lacuna within the Marxist IR tradition—the gap between general Marxist theories of IR and the analysis of foreign policy-making. This gap persists in equal measure in the bifurcation between the fields of general IR theory and actor-specific foreign policy analysis (FPA). For general IR theories—Marxist and non-Marxist—tend to deploy structuralist versions of theory, which relegate the problem of foreign policy-making to lesser, possibly non-theorisable, forms of inquiry. FPA is thereby demoted and subsumed under wider structural imperatives capable of cross-case generalisation. The paper moves from a critical exposition of the wider debate in IR and FPA of attempts to close this gap, via a critique of dialectical materialism and systematic dialectics, to a re-statement of the dialectic of the concrete. It concludes with a reconsideration of how dialectical thinking may bridge this gap by incorporating foreign policy as the crucial site for the active drawing together and re-articulation of multiple influences from the domestic and the foreign into a Historical Sociology of international relations.