This chapter explores the overlooked constitutional reforms and the constitution-making process in the over 550 princely states spread across 45 per cent of the subcontinent’s territory that were not part of British India. We argue that the constitutional processes in the princely states were fundamental to the subsequent successful merger of the states and to the making of the Indian Union. Constitutionalism in the princely states was an insistent refrain to India’s constitution making and became the standard language through which to think about and act on political aspirations for democratic government. The numerous parallel constitution-making processes in the states produced comparable constitutional templates that could ultimately be assembled into the new Indian constitution. The chapter analyses constitutionalism within the states, among different states and between the states and the Constituent Assembly. It examines the understudied constitution making process in Rewa and Ratlam states, the formations of unions of states, and finally looks at Manipur state in the north-eastern frontier of India to show the limits of the constitutional process of integration.