The open access publication of this book has been published with the support of the Swiss National Science Foundation. The volume offers new and unexplored perspectives on federalism and its relationships with diversity accommodation. It represents the first structured attempt to use federal theory and practice to frame several phenomena of governance in the area of diversity management. Federalism is here tested as a theoretical and practical tool that may contribute to a better understanding of phenomena such as non-territorial autonomy, participatory democracy and legal pluralism. This volume unveils the theoretical potential of federalism in explaining complex pluralist legal systems: This theoretical function may be the 21st century dimension of federalism.