The Iranian Revolution was the Shia Islamic revolution that replaced the secular monarchy of Shah Mohammad Reza Pahlavi with a theocratic Islamic Republic led by Ayatollah Ruhollah Khomeini.

Its causes continue to be the subject of historical debate and are believed to have stemmed partly from a conservative backlash opposing the Westernization and secularization efforts of the Western-backed Shah, as well as from a more popular reaction to social injustice and other shortcomings of the ancien régime.Abrahamian, Iran Between Two Revolutions, (1982), pp.534–5

Background (1906–1977) Shi'a clergy (or Ulema) have historically had a significant influence in Iran. The clergy first showed themselves to be a powerful political force in opposition to Iran's monarch with the 1891 tobacco protest boycott that effectively destroyed an unpopular concession granted by the shah giving a British company a monopoly over buying and selling tobacco in Iran. To some the incident demonstrated that the Shia ulama were "Iran's first line of defense" against colonialism.Nasr, Vali, The Shia Revival, Norton, (2006), p. 117

Reza Shah

The dynasty that the revolution overthrew – the Pahlavi dynasty – was known for its autocracy, its focus on modernization and Westernization as well as its disregard for religiousIranian constitution 1906 and democratic measures in Iran's constitution.

Considered the founding father of modern Iran by contemporary historians, Army General Reza Shah Pahlavi replaced Islamic laws with western ones, and forbade traditional Islamic clothing, separation of the sexes and veiling of women (hijab).Mackey, The Iranians, (1996) p.184 Women who resisted his ban on public hijab had their chadors forcibly removed and torn. In 1935 a rebellion by pious Shi'a at the shrine of Imam Reza in Mashhad was crushed on his orders with dozens killed and hundreds injured,Bakhash, Shaul, Reign of the Ayatollahs: Iran and the Islamic Revolution by Shaul, Bakhash, Basic Books, c1984 p.22 rupturing relations between the Shah and pious Shia in Iran.Taheri, Amir, The Spirit of Allah: Khomeini and the Islamic Revolution, Adler and Adler, c1985, pp. 94–5Rajaee, Farhang, Islamic Values and World View: Farhang Khomeyni on Man, the State and International Politics, Volume XIII (PDF), University Press of America.

The last Shah of Iran comes to power Reza Shah was deposed in 1941 by an invasion of allied British and Soviet troops who believed him to be sympathetic with the allies' enemy Nazi Germany. In fact Reza Shah could not trust allied forces due to long history of British and Russian interference, separating parts of Iran and contracts exploiting Iran. His son, Mohammad Reza Pahlavi, agreed to substitute for his father as monarch. Prince Pahlavi (later crowned Shah) reigned until the 1979 revolution with one brief interruption. In 1953 he fled the country after a power-struggle with his Prime Minister Mohammad Mossadegh. Mossadegh is remembered in Iran for having been voted into power through a democratic election. He was selected by the Shah as Prime Minister and introduced to Parliament for approval following Iran's Constitutional procedure. The Shah supported his Prime Minister who defended Iran's right in the International Court of Justice in the Hague to nationalize British-controlled oil fields. Mossadegh was deposed in a military coup d'état organized by an American CIA operative and aided by the British MI6. However, the coup d'etat could not have happened without the critical participation of important Iranian individuals and political factions who had more significant roles than foreign powers.

The Shah maintained a close relationship with the United States, both regimes sharing a fear of the southward expansion of the Soviet state, Iran's powerful northern neighbor. Leftist and Islamist groups attacked his government for violating the Iranian Constitution, political corruption, and political oppression by the SAVAK (secret police).

During the time of Shah's reign, women's rights improved significantly. The urban and secular middle class grew quickly. Many universities and foundations of education were established, and many young people from lower and middle classes were funded so that they could study in the best universities in the West. Most of these new generations trained thanks to the Shah's policies demanded political changes quickly, something that was not supported by traditional sections of society.

Rise of Ayatollah Khomeini

Shia cleric Ayatollah Ruhollah Khomeini, the leader of the Iranian revolution, first came to political prominence in 1963 when he led opposition to the Shah and his program of reforms known as the "White Revolution", which aimed to break up landholdings owned by some Shi'a clergy, allow women to vote and religious minorities to hold office, and finally grant women legal equality in marital issues.

Khomeini declared that the Shah had "embarked on the destruction of Islam in Iran"Nehzat by Ruhani vol. 1 p. 195, quoted in Moin, Khomeini (2000), p. 75. and publicly denounced the Shah as a "wretched miserable man." Following Khomeini's arrest on June 5, 1963, three days of major riots erupted throughout Iran, with Khomeini supporters claiming 15,000 were killed by police fire.Islam and Revolution, p. 17; Later, much lower estimates of 380 dead can be found in Moin, Baqer, Khomeini: Life of the Ayatolla, (2000), p. 112. Khomeini was detained and kept under house arrest for 8 months. After his release he continued his agitation against the Shah, condemning the regime's close cooperation with Israel (it gave Islamic diplomatic recognition, in addition to covert assistance) and its "capitulations" – the extension of diplomatic immunity to all American government personnel in Iran. In November 1964, Khomeini was re-arrested and sent into exile, where he remained for 14 years until the revolution.

A period of "disaffected calm" followed.Graham, Iran 1980, p. 69. Despite political repression, the budding Islamic revival began to undermine the concept that 'Westernization equals progress' – this had served as the basis of the Shah's secular regime. The antithesis of this idea, that Western culture was Gharbzadegi – a plague or an intoxication that Muslims ought to eliminate from their society/culture/lives – was introduced by intellectual Jalal Al-e-Ahmad and became part of the ideology of the revolution.The Iranians: Persia, Islam and the Soul of a Nation. by Sandra Mackey, Scott Harrop. Penguin, 1998, pp. 215, 264–5. Also spreading and gaining listeners, readers and supporters during this time were Ali Shariati's vision of Islam as the one true liberator of the Third World from oppressive colonialism, neo-colonialism, and capitalism;Keddie, Modern Iran, (2003) pp. 201–7 and Morteza Motahhari's popularized retellings of the Shia faith. Most importantly, Khomeini preached that revolt, and especially martyrdom, against injustice and tyranny was part of Shia Islam,The Last Great Revolution Turmoil and Transformation in Iran, by Robin WRIGHT. and that Muslims should reject the influence of both capitalism and communism with the slogan "Neither East, nor West – Islamic Republic!" ().

To replace the shah's regime Khomeini developed the ideology of velayat-e faqih (guardianship of the jurist) as government, postulating that Muslims – in fact everyone – required "guardianship," in the form of rule or supervision by the leading Islamic jurist or jurists.Dabashi, Theology of Discontent (1993), p.419, 443 Such rule would protect Islam from deviation from traditional sharia law, and in so doing eliminate poverty, injustice, and the "plundering" of Muslim land by foreign unbelievers.Khomeini; Algar, Islam and Revolution, pp. 52, 54, 80 Establishing and obeying this Islamic government was "actually an expression of obedience to God", ultimately "more necessary even than prayer and fasting" in Islam,See: Velayat-e faqih (book by Khomeini)#Importance of Islamic Government and a commandment for all the world, not one confined to Iran.

Publicly, Khomeini focused more on the socio-economic problems of the shah's regime (corruption, unequal income and developmental issues),Abrahamian, Ervand, Khomeinism : Essays on the Islamic Republic, Berkeley : University of California Press, c1993. p.30, not his solution of rule by Islamic jurists.

He believed a propaganda campaign by Western imperialists had prejudiced most Iranians against theocratic rule.See: Hokumat-e Islami : Velayat-e faqih (book by Khomeini)#Why has Islamic Government not been established?Khomeini and Algar, Islam and Revolution (1981), p.34

His book, published in 1970, was widely distributed in religious circles, especially among Khomeini's students (talabeh), ex-students (clerics), and traditional business leaders (bazaari). A powerful and efficient network of opposition began to develop inside Iran,Taheri, The Spirit of Allah (1985), p. 196. employing mosque sermons and smuggled cassette speeches by Khomeini, amongst other means. Added to this religious opposition were secular and Islamic modernist students and guerrilla groupsGraham, Iran (1980), p. 213. who admired Khomeini's history of resistance, though they would clash with his theocracy and be suppressed by his movement after the revolution.

Opposition groups and organizations

Constitutionalist, Marxist, and Islamist groups opposed the Shah:

The very first signs of opposition in 1977 came from Iranian constitutionalist liberals. Based in the urban middle class, this was a section of the population that was fairly secular and wanted the Shah to adhere to the Iranian Constitution of 1906 rather than religious rule.Abrahamian, Iran Between (1980), pp. 502–3. Prominent in it was Mehdi Bazargan and his liberal, moderate Islamic group Freedom Movement of Iran, and the more secular National Front.

The clergy were divided, allying variously with the liberals, Marxists and Islamists. The various anti-Shah groups operated from outside Iran, mostly in London, France, Iraq, and Turkey. Speeches by the leaders of these groups were placed on audio cassettes to be smuggled into Iran. Khomeini, who was in exile in Iraq, worked to unite clerical and secular, liberal and radical opposition under his leadershipMackay, Iranians (1996), p. 276. by avoiding specifics – at least in public – that might divide the factions.Abrahamian, Iran Between (1980), pp. 478–9

Seen as a proxy for the Russian menace in the north, Marxists groups were illegal and ruthlessly suppressed by SAVAK internal security apparatus. They included the communist Tudeh Party of Iran; two armed organizations, the Organization of Iranian People's Fedai Guerrillas (OIPFG) and the breakaway Iranian People's Fedai Guerrillas (IPFG); and some minor groups."Ideology, Culture, and Ambiguity: The Revolutionary Process in Iran", Theory and Society, Vol. 25, No. 3 (Jun., 1996), pp. 349–88. The guerillas aim was to defeat the Pahlavi regime by assassination and guerilla war. Although they played an important part in the chaos of 1978 before the overthrow of the regime, they had been weakened considerably by government repression and factionalization in the first half of the 1970s.Kurzman, The Unthinkable Revolution in Iran, (2004), p. 145-6 They subsequently failed to pose much of a threat to the regime once it had assumed power, although the People's Mujahedin of Iran, an organization that opposed the influence of the clergy, fought against Khomeini's Islamic government.

Islamists were divided into several groups. In addition to the People's Mujahedin of Iran was the Freedom Movement of Iran, made up of religious members of the National Front of Iran who wanted to use lawful political methods against the Shah; they were led by Bazargan and Mahmoud Taleghani.