The article addresses the constitutional changes of Thailand and Vietnam through a comparative perspective. In doing so, it takes functionalism as the starting point to tackle common issues of constitutional concern, i.e. the protection of rights, the form of government, constitutional supremacy, while being carefully attuned to local particularities as well as political mindsets, cultures, and jurisprudential principles. It aims to display constitutions as «a site for mediating universal values and local particularities», thus contributing to enrich the scholarly discourse on constitutionalism in Southeast Asia and on comparative constitutional law in general.