Contemporary Iran plays a special role in the history of Islamic constitutionalism, as the constitution of 1979 was the first attempt since the debates over Pakistan’s Islamic Republic to derive the basic law of a modern state from Islamic principles. The Islamic Republic that came into being that year combines, as the name implies, Islamic and republican principles, which find institutional expression in a state that combines theocratic and republican organs. Iran was thus the first state in modern times in which sections of the ulema took direct control of the state. In this article we will first provide a historical context for the emergence of the idea of an Islamic state and its central principle, the dominion of the Shiʿi jurisprudent or velāyat-e faqih (from Arabic wilāyat al-faqih). This will be followed by a discussion of the process of constitution making, leading to a close examination of the constitution itself and the debates to which its various parts gave rise.