The medieval officium, also known as the liturgy of the hours or Divine Office, was the principal spiritual work monks and clergy performed, every day, for the entirety of their lives. The office was organized around the reading of biblical passages, commentary, and hagiographical narratives, which were further contemplated through communally sung texts. Matins, before daybreak was the biggest portion of the office, with important feast days having between nine and twelve different lessons (this difference corresponding to monastic or secular houses, respectively). At daybreak followed the offices of Lauds, and the shorter services of the little hours: First was Prime, Terse, Sext, Nones, and then Vespers in the afternoon, and Compline after nightfall. Between these meetings where texts were read and sung, monks and clergy celebrated two masses, the morrow and major Mass (after Terce), as well as devotional masses for the dead, and carried out other duties. In all, the daily cycle of chants and texts surpassed more than 200 individual pieces.

The performance of this large quantity of communal reading and singing was a product of devotional changes in medieval monasticism. Before the eleventh century the office liturgy was less rigorous and more loosely organized. From the ninth century, secular clergy attending the bishop's community were generally organized according to the rule of Aachen. This permitted them to live independent lives, reside in their private residences, and essentially tend to the duties of the Church in a non-rigorous manner. As a consequence of the Cluniac Benedictine reforms and the birth of reformed orders (e.g. Cistercian), the performance of the Divine Office witnessed a profound rethinking and systematic reorganization. The codification of liturgical praxis positioned its performance at the core of the brethren's life.