The Augustinian monastic order is constituted at the Lecceto Monastery when Pope Alexander IV issues a papal bull Licet ecclesiae catholicae.

Augustinians are members of several religious orders that follow the Rule of Saint Augustine, written about 400 A.D. by Augustine of Hippo. There are two distinct types of Augustinians in Catholic religious orders dating back to the 12th–13th centuries:

• Various congregations of Canons Regular follow the Rule of Saint Augustine, embracing the evangelical counsels and leading a semi-monastic life, while remaining committed to pastoral care appropriate to their primary vocation as priests. They generally form one large community which might serve parishes in the vicinity, and are organized into autonomous congregations.
• Several orders of friars who live a mixed religious life of contemplation and apostolic ministry. The largest and most familiar is the Order of Saint Augustine (O.S.A.), founded in 1244 and originally known as the Hermits of Saint Augustine (O.E.S.A.). They are commonly known as the Austin Friars in England. Two other orders, the Order of Augustinian Recollects (O.A.R.) and the Discalced Augustinians (O.A.D.), were once part of the original Order under a single Prior General. The Recollects, begun in 1588 as a reform movement in Spain to recover the Order's eremitical roots, became autonomous in 1612. At the 100th General Chapter of the Order held in Rome in May 1592, those seeking reform of their way of life came to be called the Discalced (barefoot) and were authorized to seek their goals as an semi-independent branch. They were raised to the status of a separate mendicant Order in 1610.