O.S.B.

Order of Saint Benedict

Ordo Sancti Benedicti
Design on the obverse side of the Saint Benedict Medal
Abbreviation	OSB
Motto	Ora et Labora (Latin, "Pray and Work")
Formation	c. AD 529; 1488 years ago (529)
Founder	Benedict of Nursia
Type	Catholic religious order
Headquarters	Church of Sant'Anselmo all'Aventino, Rome
Main organ	Benedictine Confederation
Website	osb.org

The Order of Saint Benedict (OSB; Latin: Ordo Sancti Benedicti), also known – in reference to the colour of its members' habits – as the Black Monks, is a Catholic religious order of independent monastic communities that observe the Rule of Saint Benedict. Each community (monastery, priory or abbey) within the order maintains its own , while the order itself represents their mutual interests. The terms "Order of Saint Benedict" and "Benedictine Order" are, however, also used to refer to all Benedictine communities collectively, sometimes giving the incorrect impression that there exists a generalate or motherhouse with jurisdiction over them.

Internationally, the order is governed by the Benedictine Confederation, a body, established in 1883 by Pope Leo XIII's Brief Summum semper, whose head is known as the Abbot Primate. Individuals whose communities are members of the order generally add the initials "OSB" after their names.

The monastery at Subiaco in Italy, established by Saint Benedict of Nursia circa 529, was the first of the dozen monasteries he founded. He later founded the Abbey of Monte Cassino. There is no evidence, however, that he intended to found an order and the Rule of Saint Benedict presupposes the autonomy of each community. When Monte Cassino was sacked by the Lombards about the year 580, the monks fled to Rome, and it seems probable that this constituted an important factor in the diffusion of a knowledge of Benedictine monasticism.