The Order of Cistercians of the Strict Observance (O.C.S.O.: Ordo Cisterciensis Strictioris Observantiae) is a Roman Catholic religious order of cloistered contemplative monastics who follow the Rule of St. Benedict. A branch of the Order of Cistercians, they have communities of both monks and nuns, commonly referred to as Trappists and Trappistines, respectively.

History

The order takes its name from La Trappe Abbey or La Grande Trappe, located in the French province of Normandy. A reform movement began there in 1664, in reaction to the relaxation of practices in many Cistercian monasteries.Armand Jean le Bouthillier de Rancé, originally the commendatory abbot of La Trappe, led the reform. As commendatory abbot, de Rancé was a layman who obtained income from the monastery but had no religious obligations. After a conversion of life between 1660 and 1662, de Rancé formally joined the abbey and became its regular abbot in 1663. In 1892 the reformed "Trappists" broke away from the Cistercian order and formed an independent monastic order with the approval of the Pope.