India, as the world’s largest constitutional democracy, represents a unique political experiment in balancing national unity with regional diversity. The Indian constitutional framework recognises pluralism, federalism, and democratic decentralisation while simultaneously preserving the sovereignty and integrity of the nation-state. This research article critically examines the relationship between constitutional democracy and regional self-determination in India, with special reference to West Bengal and Assam. The study explores how linguistic identity, ethnic aspirations, regional nationalism, and federal arrangements interact within the constitutional framework of India. It further analyses the political and constitutional challenges arising from regional autonomy movements, citizenship debates, migration issues, and ethnic conflicts in these two states. The article argues that India’s constitutional structure has largely succeeded in accommodating regional aspirations through asymmetric federalism, democratic participation, and constitutional safeguards, though tensions between centralisation and regional autonomy continue to shape contemporary politics.