Salvador Allende was the president of Chile from 1970 until his 1973 suicide, and head of the Popular Unity government; he was a Socialist and Marxist elected to the national presidency of a liberal democracy in Latin America. In August 1973 the Chilean Senate declared the Allende administration to be "unlawful," Allende's presidency was ended by a military coup before the end of his term. During Allende's three years, Chile gradually transitioned into a socialist state.

During his tenure, Chilean politics reached a state of civil unrest amid political polarization, hyperinflation, lockouts, economic sanctions, CIA-sponsored interventionism and a failed coup in June 1973. Allende's coalition, Unidad Popular, faced the problem of being a minority in the congress and it was plagued by factionalism.

On 11 September 1973, a successful coup led by General Augusto Pinochet overthrew the government of Allende.

During the bombing of the presidential palace by the Chilean Air Force, President Allende, after mounting a brief armed resistance against the military, eventually committed suicide. In Chilean historiography, Allende's presidency is the last one of the period known as the "Presidential Republic" (1925–1973).