1978 – Shah Mohammed Reza Pahlavi’s authoritarian rule sparks demonstrations and riots.
February 1, 1979 – Ayatollah Ruhollah Khomeini returns to Iran, after 14 years in exile, to lead the country.
October 22, 1979 – The Shah is allowed to enter the United States to receive medical treatment for cancer.
November 5, 1979 – The Iranian government cancels military treaties with the US and the Soviet Union, treaties that would permit US or Soviet military intervention.
November 6, 1979 – Premier Mehdi Bazargan and his government resign, leaving Ayatollah Khomeini and the Revolutionary Council in power.
November 14, 1979 – President Carter orders Iranian assets in US banks frozen.
November 17, 1979 – Khomeini orders the release of female and African-American hostages. They are released November 19 and 20, bringing the total number of US hostages to 53.
December 15, 1979 – The Shah leaves the United States for Panama.
March 1980 – The Shah returns to Egypt.
April 7, 1980 – President Carter cuts diplomatic ties with Iran, announcing further sanctions and ordering all Iranian diplomats to leave the United States.
April 25, 1980 – Eight US servicemen are killed when a helicopter and a transport plane collide during a failed attempt to rescue the hostages.
July 11, 1980 – Another hostage is released due to illness. The total number of US hostages is now 52.
July 27, 1980 – The Shah dies of cancer in Egypt.
September 12, 1980 – Ayatollah Khomeini sets new terms for the hostages’ release, including the return of the late Shah’s wealth and the unfreezing of Iranian assets.
November 1980-January 1981 – Deputy Secretary of State Warren Christopher and his delegation work through mediators in Algeria to negotiate the release of the hostages.
January 19, 1981 – The United States and Iran sign an agreement to release the hostages and unfreeze Iranian assets.
January 20, 1981 – The remaining 52 US hostages are released and flown to Wiesbaden Air Base in Germany.