 At the age of twelve, François entered the Order of S. Antoine en Viennois, where he came under the tutelage of Abbot Theodore Mitte de S. Chamond (1495-1527).In due course, François de Tournon became Preceptor of the monastery, and then became the 21st Abbot of the Order of S. Antoine in 1542, a position which he continued to hold until 1555.By command of Pope Boniface VIII (1295-1303) the members of the Order of S. Antoine followed the Rule of S. Augustine and were considered Canons Regular of S. Augustine (CRSA).