He attended school in Cochabamba and then entered the military academy, from which he was expelled because he supported the Germán Busch government. He was subsequently readmitted and graduated in 1943.
Barrientos entered the Military College of Aviation and studied briefly in the United States, earning his wings in April 1945.
He supported the Gualberto Villarroel López coup in 1943 and participated in the organization of the 1944 peasant congress. Because of his involvement in the 1949 civil war against the entrenched elites, he was retired from the army. He risked his life for the Nationalist Revolutionary Movement (MNR) revolution in April 1952, flying supply missions from Santa Cruz. His loyal support of the MNR led to Barrientos’ rapid rise in the military from captain to general of the air force and head of the party’s military cell.
Barrientos successfully pressured Víctor Paz Estenssoro to nominate him as a vice presidential running mate for the elections of May 1964. However, Paz’s third term ended precipitously with a coup on November 3, 1964, by Barrientos and General Alfredo Ovando Candia. Barrientos and Ovando assumed temporary executive control. Barrientos resigned from the co-presidency, leaving Ovando in charge in January 1966 to run in the July elections.
On April 27, 1969, Barrientos’ heliocopter mysteriously crashed, ending his life and presidency.