Constitutional identity has become one of the most important and hotly contested concepts in contemporary constitutional theory and practice. It has been repeatedly invoked in debates concerning EU integration, constitutional reform and revolution, and the spread of ethno-nationalist populism, democratic backsliding, and constitutional retrogression. Yet, the concept's precise foundations, meaning, scope, and dynamics of continuity and change remain somewhat unclear and under-explored. This contemporary and definitive volume aims to address this stark gap. Featuring some of the world's leading scholars of comparative constitutionalism, constitutional theory, and constitutional politics, this book provides a comprehensive, first-of-its-kind theoretical, comparative, normative, and empirical account of the concept of constitutional identity. It will be of great interest to scholars, students, jurists, and constitutional drafters alike.