What explains the European Union’s successes and failures in producing a grand strategy? Conceptualizing grand strategy as a composite commonplace linking together understandings of scene, agent, purpose and means (tetrad), I contend that the European Union has a grand strategy. In the early 1990s, advocates succeeded in institutionalizing the diffusion strategy. A decade later, however, the advocates of the European Security Strategy failed to do so. My explanation of this descriptive finding focuses on the constellation of prior agreements on the components of the tetrad. In both cases, widely taken-for-granted agreements on a recently shifted scene (security environment) provided openings for the advocates. But only the advocates of diffusion had the opportunity to work with equally widely taken-for-granted agreements on agent (identity), purpose (interest) and means (power). The advocates for the European Security Strategy, by contrast, were lacking such a favourable social context. Borrowing from rhetorical studies, this study makes a threefold contribution to the study of grand strategy. It moves beyond the literature’s statism; shows that grand strategy is constituted by interpretations not just of power and interest, but also of the security environment and identity; and clarifies that explanations of the making of grand strategy need to inquire into the making of agreements rather than merely the interplay of material forces. My findings that the European Union has a grand strategy and came to adopt it by building a new agreement upon already-existing ones also have implications for the study of European Union foreign policy and International Relations Theory.