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 also follow the Rule of Saint Augustine, embrace the evangelical counsels and lead 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 (OSA), founded in 1244 and originally known as the Hermits of Saint Augustine (OESA). They are commonly known as the Austin Friars in England. Two other orders, the Order of Augustinian Recollects and the Discalced Augustinians, were once part of the OSA under a single prior general. The Recollects, founded in 1588 as a reform movement in Spain, became autonomous in 1612. The Discalceds became an independent congregation in 1592, and were raised to the status of a separate mendicant order in 1610.

Monasticism, also called monachism or monkhood, is a religious way of life in which one renounces worldly pursuits to devote oneself fully to spiritual activities. Monastic life plays an important role in many Christian churches, especially in the Catholic, Orthodox and Anglican traditions as well as in other faiths such as Buddhism, Hinduism, and Jainism. In other religions, monasticism is generally criticized and not practiced, as in Islam and Zoroastrianism, or plays a marginal role, as in modern Judaism.

The Monastery of the Holy Saviour at Lecceto in Tuscany, was the principal House of the order of the Hermit Friars of Saint Augustine in 1256, when Pope Alexander IV constituted the Augustinian order internationally. It was dedicated to Jesus as Saviour.