[1] He joined the Order of Friars Minor Capuchin on December 8, 1913, and was later sent to Genoa, Italy, to continue his novitiate in 1915.
Receiving the habit on the following September 8, Barbieri made his solemn vows and took the name Antonio María.
He declined a professorship at a prestigious university in Rome and returned to Uruguay, where he served as a pastor in the local Capuchin friary.
[1] Barbieri was a close associate of Carlos Carmelo Vasconcellos Motta when the first episcopal conferences of Latin American bishops began in the mid-1950s.
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).