The chapter argues that the growing interdependence of national and post-national constitutional structures has (as is perhaps most evident in the European context) triggered a heightened contentiousness regarding the nature and status of constitutions, the institutions endowed with powers of ultimate constitutional adjudication, and the justification of constitutional orders. To address this contentiousness, the chapter provides a political-sociological analysis, which emphasizes the interrelated roles of different constitutional actors (including political and legal actors, but also different societal forces), their different ways of interpreting the constitution, and their different understandings of the national and transnational domains.