This paper challenges the commonly held perception that grand theory is irrelevant for policy. Policy, it is often argued, is in need of detailed case-oriented empirical analysis and instrumental policy recommendations rather than any sweeping generalizations or lofty ideas emanating from grand theory. Notwithstanding, this paper argues that grand theory has an underestimated relevance for policy. To be able to see and appreciate this, the notion of policy relevance must be expanded. Whereas grand theory and grand concepts such as Realism, Liberalism, Constructivism, or Marxism do not provide case-specific knowledge or recommendations, they provide general roadmaps, conceptualization of world affairs, and also have a symbolic function, legitimating or challenging established policy paradigms. Policymakers, akin to grand theorists, arguably like to make sweeping statements and generalizations. Drawing on theory and findings in public policy studies, here applied to international relations and foreign policy, this paper suggests conditions under which grand theory can be relevant for policy.