The Constitution of Poland does not use the term ‘constitutional identity’, but this concept has been developed and expounded by the Constitutional Tribunal. The chapter argues that the constitutional identity has become both a normative and a descriptive concept in the constitutional jurisprudence. On the one hand, the Tribunal used the concept of constitutional identity to determine the limits of the competence for conferring power to the European Union, excluding certain subject matters from the scope of the conferral. On the other hand, references to constitutional identity in the Tribunal’s case law denote axiological similarity, equivalence, or convergence between the EU and the national legal order. Moreover, the descriptive notion of constitutional identity has been used to signify the distinctiveness of the Polish constitutional order, which has recently been employed by the populist government to claim the right to introduce reforms undermining the rule of law as an aspect of national sovereignty.