Providing a comprehensive view of the constitutional architecture of federations, contributors address change and development in federal states from the standpoint of constitutional revision and reform. Oftentimes change comes from the constituent units that together form a federation. With this in mind, political scientists and legal scholars from across Europe and North America address three important questions. First, what is the scope of national space - the range of discretion and autonomy in constitutional design and development - that is available to the sub-national units in federal system? Second, to what extent have the sub-national units occupied the constitutional space available to them? Third, what have been the effects of constitutional initiatives by sub-national units within their constitutional space on national constitutional development (vertical federalism), on constitutional development in other sub-national units (horizontal federalism), and on political development within their own borders? A comparative, interdisciplinary approach to constitutionalism in federal systems, this volume will be of particular interest to scholars studying federalism, comparative politics, public law, and political development. Contributors include Michael Burgess (University of Kent) and G. Alan Tarr (Rutgers University-Camden), John J. Dinan (Wake Forest University), Arthur Gunlicks (University of Richmond), Peter Bu?jager (University of Innsbruck), Jens Woelk (University of Trento), Nicolas Schmitt (University of Fribourg), Patrick Peeters (University of Leuven), Gerald Baier (University of British Columbia), Stephen Tierney (University of Edinburgh), Carlos Viver (University of Barcelona), Francesco Palermo (University of Verona), Anneli Albi (University of Kent), Ornella Porchia (University of Turin).