An Augustinian is a member of a Roman Catholic religious community or order that follows the Rule of Saint Augustine, a set of guidelines for religious life written by Augustine of Hippo around 400 A.D.

The term broadly refers to members of several religious orders, including the Order of Saint Augustine (OSA), founded in 1244, as well as related congregations such as the Augustinian Canons, the Augustinian Hermits, the Augustinian Recollects, and others.

Key characteristics of Augustinians include:

• They live according to the Rule of Saint Augustine, which emphasizes community life, sharing of goods, and a spirit of unity and harmony, inspired by the early Christian community described in the Acts of the Apostles.

• Augustinians take vows of chastity, poverty, and obedience, and live a life that combines contemplation with active ministry such as education, mission work, and pastoral care.

• The Order of Saint Augustine is an international Catholic religious community with about 2,800 members in 47 countries.

• Augustinians are known for their commitment to communal living, spiritual growth, and service to others, following Augustine's teachings on the search for God, love of neighbor, and pursuit of truth.

Historically, Augustinians have been influential in the Church and society, counting among their members saints, scholars, and even a pope (Pope Leo XIV, elected in 2025).

In summary, an Augustinian is a Catholic religious person who lives by the spiritual and communal principles established by Saint Augustine, belonging to one of several related religious orders dedicated to prayer, study, and service.