The Institutional Revolutionary Party is a political party in Mexico that was founded in 1929 and held uninterrupted power in the country for 71 years, from 1929 to 2000, first as the National Revolutionary Party, then as the Party of the Mexican Revolution and finally as the PRI beginning in 1946.

Plutarco Elías Calles was a Mexican soldier and politician who served as President of Mexico from 1924 to 1928. After the assassination of Álvaro Obregón, Elías Calles founded the Institutional Revolutionary Party and held unofficial power as Mexico's de facto leader from 1929 to 1934, a period known as the Maximato. Previously, he served as a general in the Constitutional Army, as Governor of Sonora, Secretary of War, and Secretary of the Interior. During the Maximato, he served as Secretariat of Public Education, Secretary of War again, and Secretary of the Economy. During his presidency, he implemented many left-wing populist and secularist reforms, opposition to which sparked the Cristero War.