This is the first comprehensive analysis of the role of subnational parliaments in the EU policymaking system. The contributions analyze the dynamic resulting from the new provisions of the Lisbon Treaty, which was meant to strengthen the role of parliaments at all levels of the EU system and, thereby, improve the EU's democratic legitimacy. The book addresses conceptual questions arising from studies on parliaments, Europeanization, and federalism. Six case studies present the situation in those EU member states with subnational parliaments endowed with legislative competences.