He was one of the cardinal electors in the 1963 conclave, participated in the Second Vatican Council (1962–1965), and during the 1960s was recognized for his long periods of service as a theologian and historian with his promotion to the "Instituto Histórico y Geográfico del Uruguay" (Historical and Geographical Institute of Uruguay). Barbieri resigned as Montevideo's archbishop on November 17, 1976, after thirty-five years of service. When he turned eighty in 1972, however, the Cardinal was not permitted to attend any future conclaves, and he died quietly less than a year into Pope John Paul II's pontificate, at age 86.