Art. 4(2) TEU provides that the European Union (EU) shall respect Member States’ national identities, inherent in their fundamental structures, political and constitutional, inclusive of regional and local self-government. This chapter examines the extent of this duty resting on the EU with regard to both the content and normative functions of the identity clause. Analysed against the backdrop of multilevel constitutionalism, an understanding of the identity clause as a Verbundnorm is proposed. The chapter outlines this understanding and shows how it helps untangle and explain in detail the modality and extent of the connection between the identity clause and the Member States’ constitutional identity debates. Building on this, the chapter then explains how application of the identity clause can be aimed at establishing and ensuring the functioning of the European legal system as a whole.