This book assesses territorial governance (that is, all forms of subnational governance) as a constitutional artefact in five Southeast Asian countries - Indonesia, Malaysia, Myanmar, the Philippines, and Thailand. Starting with the linked ideas of localism and subsidiarity, the argument is that these states have used various forms of subsidiarity for dealing with ethnic and religious pluralism and the social diversity for which Southeast Asia is especially noted. Territorial governance mechanisms discussed range from decentralisation to special regional autonomy, federalism, and local government, including village autonomy. A silent revolution has occurred in which our view of these states as highly centralised 'developmental states' is in need of serious modification. Southeast Asia, the book argues, presents a high degree of originality in the framing of territorial governance.