Existing research suggests that the European Union (EU) has avoided the formal construction of a supranational culture. Theories in economic sociology predict that market building should entail the concomitant articulation of basic cultural material, above all of ontological and normative notions about the world. In this article we confirm that the EU has formally engaged in cultural construction. Through its system of secondary laws, the EU has in fact produced complex webs of ontological notions about the essence of objects, activities and agents, and of normative notions about the desirability of various situations. Analysis of the content of EU directives and regulations in the areas of working conditions, flora and fauna, and honey supports this claim. Analysis of national reactions and cultural contexts highlights the salience and distinctiveness of the emerging supranational culture. Evidence that Mercosur too has engaged in the production of ontological and normative notions suggests that, in line with the expectations of economic sociology, the EU is not unique, though the two markets can construct different notions when addressing identical subject matters. The implications of the findings for European enlargement and the comparative study of common markets are discussed.