The 1979 Islamic revolution in Iran would never have happened without the kind of track record we had in that country over the previous 25 years.
Although the overthrow of Mossadegh (Kermit Roosevelt, the CIA and British MI6) and the restoration of the Shah to the Peacock throne did cause widespread and lingering resentment of the US, the Shah was his own worse enemy in terms of sowing the seeds of revolution. Mohammed Mossadegh's desire to nationalize oil and his associations with the Communists (Tudeh party) may have led to a different kind of revolution.
Historically, you can go back to 1921 and the British-backed military coup d'état led by Persian Cossacks Brigade officer Reza Khan, who in April 1926 took the crown for himself as His Imperial Majesty Reza Shah Pahlavi, beginning the so-called Pahlavi Dynasty. His rule brought a modernization of the political and social systems and a substantial reduction in the power of the clergy and tribal leaders. However along with the reforms came increasing repression and social unrest. These are where the real seeds of the 1979 revolution came from. The mullahs were always at odds with the Shah and they probably would have challenged Mossadegh's government as well.
YOU ARE SO INFORMATIVE!
That's a valid point. What I find interesting is that in recent (say, post-WW2) history, associations with Communists or radical Muslims were probably not considered egregious offenses by the U.S. But the moment someone like Mohammed Mossadegh, Ho Chi Minh, or Slobodan Milosevic announces that he wants to "nationalize" a vital part of his country's economy, the U.S. will always react as if the future of civilization is at stake.