The Order of Saint Augustine (Latin: Ordo Fratrum Sancti Augustini), abbreviated OSA, is a mendicant religious order of the Catholic Church. It was founded in 1244 by bringing together several eremitical groups in the Tuscany region who were following the Rule of Saint Augustine, written by Augustine of Hippo in the fifth century.
They are also commonly known as the Augustinians, Austin friars, or Friars Hermits and, until 1968, as the Order of Hermits of Saint Augustine (Latin: Ordo eremitarum sancti Augustini; abbreviated O.E.S.A).