He took a doctor's degree in Canon Law. He studied in Rome and specialized in Canon Law at Berkley University (California, U.S.A.) under the direction of Professor Stephan Kuttner. Since 1959, he has been Professor at the Pontifical University in Salamanca. He was nominated 'Doctor Honoris Causa' at Siena (Italy) and Lisbon Universities. He is a member of the 'Senese degli Intronati' Academy, the Portuguese Academy of History, the Portuguese Academy of Sciences and the Academy of Sciences in Toledo.
He has written 35 individual and collective books and about 270 articles. The list of the articles appears at the beginning of the miscellany that his partners from Europe and America dedicated him. It was coordinated by Professor Peter Linehan (Cambridge University, England) and published by Card. Alphns M. Stickler with the title Life, Law and Letters: Historical Studies in Honour of Antonio García García, Rome, 1998. He also wrote History of Bretoña, his native town. He is the president of the Institute of History. He is director of the 'Synidicon Hispanum'.
He got the 'Humanities' Prize, awarded by the Government of Castille and Leon, 1995. He got 'Galileo Galilei' International Prize, Pisa, 1994.