From the 6th century onward, most of the monasteries in the Catholic West belonged to the Benedictine Order. Owing to the stricter adherence to a reformed Benedictine rule, the Abbey of Cluny became the acknowledged leading centre of Western monasticism from the later 10th century. Cluny created a large, federated order in which the administrators of subsidiary houses served as deputies of the abbot of Cluny and answered to him. The Cluniac spirit was a revitalising influence on the Norman Church, at its height from the second half of the 10th century through the early 12th century.

The next wave of monastic reform came with the Cistercian movement. The first Cistercian abbey was founded in 1098, at Cîteaux Abbey. The keynote of Cistercian life was a return to a literal observance of the Benedictine rule, rejecting the developments of the Benedictines. The most striking feature in the reform was the return to manual labour, and especially to field-work. Inspired by Bernard of Clairvaux, the primary builder of the Cistercians, they became the main force of technological advancement and diffusion in medieval Europe. By the end of the 12th century, the Cistercian houses numbered 500, and at its height in the 15th century the order claimed to have close to 750 houses. Most of these were built in wilderness areas, and played a major part in bringing such isolated parts of Europe into economic cultivation.

A third level of monastic reform was provided by the establishment of the Mendicant orders. Commonly known as "friars", mendicants live under a monastic rule with traditional vows of poverty, chastity, and obedience but they emphasise preaching, missionary activity, and education, in a secluded monastery. Beginning in the 12th century, the Franciscan Order was instituted by the followers of Francis of Assisi, and thereafter the Dominican Order was begun by St. Dominic.