in music, settings of the public prayer service (divine office) of the Roman Catholic Church (Roman Catholicism), divided into Matins, Lauds, Prime, Terce, Sext, None, Vespers, and Compline. The early monastic communities composed a complete series of hours for morning, noon, and evening; cathedral and parish churches had incorporated all the hours by the 8th century, and by the 9th century the structure was fixed.

The musical items found in the hours include antiphons (texts usually sung before and after psalms), and psalm tones (formulas for intonation of psalms), responsories (texts usually sung after lessons, or scriptural readings), hymns, and lesson tones. The first musical settings of the hours were sung in plainsong (one voice part, in unmeasured rhythm). As in the case of the mass, the music of the hours absorbed tropes, or musical and textual additions, especially in the responsories of Matins (see trope; Gregorian chant).

Settings of the hours preserve some of the oldest examples of polyphony, the art of simultaneous combination of melodies. Thus the Winchester Troper, a 10th- or 11th-century manuscript copied for services for Winchester Cathedral, contains one of the largest body of early two-part settings of the responsories for Matins. The Spanish Codex Calixtinus (about the 12th century) also includes two-part polyphony for the Matins responsories.

The polyphony common at the monastery of Saint-Martial at Limoges in France was expanded by Léonin, a composer at Notre-Dame Cathedral, Paris, c. 1160–80, in his two-part responsories for Matins. His successor, Pérotin, expanded the work of Léonin, composing not only in two parts but also in three and four parts. Both men worked on the Magnus Liber Organi (“Great Book of Organum”), a collection of two-part organums for the entire church year.

In the 15th century polyphonic settings for Vespers were most common, but there are some settings of responsories for Matins and hymns for Lauds. The Burgundian Guillaume Dufay especially, as well as another Burgundian Gilles Binchois, and the Englishman John Dunstable provided a standard repertoire that survives in manuscripts all over Europe. This repertoire includes Vesper hymns, psalms, antiphons, and Magnificats (settings of the canticle of the Virgin Mary) in three-part treble-dominated style (elaborate top part over two often instrumental, slower moving lower parts). They also used three-part fauxbourdon style, in which the middle voice moves in parallel to the upper part at the interval of a fourth below it, while the lowest part moves in parallel sixths (as in E–C) with the upper part. Psalm settings became more frequent only after 1450. The plainchant psalm-tone formula sometimes alternates with a polyphonic three-part setting, often in fauxbourdon style. By 1475 melodic imitation was increasingly used in all the musical settings, and four-part texture became standard.

In the 16th century renewed interest arose in the polyphonic settings of the hours. The Lutheran publisher Georg Rhau brought out several Vesper publications between 1538 and 1545. Consequent to the Roman Catholic liturgical reforms promoted by the Council of Trent (1545–63), cycles of hymns and Vesper services as well as settings of Matins, Lauds, and Compline for the major feasts appeared. These were performed in many local churches and newly formed seminaries. The psalms were now set in falsobordone style: a four-part chordal texture having the plainchant psalm tone in the upper part.

Very important in the 16th century were the settings of Matins and Lauds for Thursday, Friday, and Saturday of Holy Week during the service of Tenebrae (“darkness”), in which 15 candles were individually extinguished until the church was in total darkness. In Matins, there are nine lessons, each concluding with a responsory. The first three lessons are taken from the Book of Lamentations in the Bible. Numerous polyphonic settings were made of Tenebrae texts. Among the most famous are the Spaniard Tomás Luis de Victoria's Lamentations and Responsories (1585). With Claudio Monteverdi's Vespers (1610), a new style emerges. Orchestrally inspired church services revolutionized the polyphonic tradition of ecclesiastical music.

In the 18th century Wolfgang Amadeus Mozart wrote two Vesper services for soloists, chorus, and orchestra. In the 19th century attempts were made to revive the singing of Vespers by republishing 16th-century settings. Composition in this style was also encouraged by the Cecilian movement (founded 1868), which promoted reform in Roman Catholic church music.

In the 17th and 18th centuries the Lamentations were set to music for solo voices and musical instruments. In the 20th century settings of the Lamentations and responsories have been composed by Igor Stravinsky (1958), Ernst Krenek (1957), and Francis Poulenc (1962).