The referendum that established Iran as an Islamic Republic in 1979 marked a pivotal moment following the Iranian Revolution, which had begun in earnest in the late 1970s due to growing dissatisfaction with Shah Mohammad Reza Pahlavi's autocratic rule. The Shah’s government faced widespread criticism for its oppressive measures, socio-economic disparities, and Westernization policies, which many Iranians, particularly religious and traditional sectors, opposed. Ayatollah Ruhollah Khomeini emerged as the leading figure of the opposition, articulating a vision of an Islamic government based on the principles of Shia Islam. His return from exile galvanized the masses, culminating in mass protests and civil unrest against the Shah.On April 1, 1979, a nationwide referendum was held where the vote resulted in 99% approval for the establishment of an Islamic Republic. This overwhelming mandate effectively ended the monarchy that had ruled Iran for thousands of years, leading to the establishment of a new political order that emphasized Islamic law and governance. The referendum symbolized a dramatic shift in Iranian society, reflecting the people's desire for self-determination and a direct challenge to Western domination in the region. The establishment of the Islamic Republic also initiated a series of changes within Iran, from the legal system to cultural norms, significantly impacting Iranian and Middle Eastern politics for decades to come.