An office hymn has formed a part of the Daily Offices of western Christians since the time of St. Ambrose in the fourth century. Ambrose is credited with beginning the practice of singing hymns in his cathedral, and the earliest surviving Latin office hymns are attributed to him. The office hymns at noonday and compline are chosen for the time of day (see the headings Noonday and Compline in The Hymnal 1982), as are those for Morning and Evening Prayer on ordinary weekdays. Proper hymns are used during the major seasons of the liturgical year and on festivals. In the Prayer Book offices of Morning and Evening Prayer, the office hymn is typically sung after the collects, where the rubrics permit the singing of a hymn or anthem (BCP, pp. 58, 71, 101, 125). A suitable office hymn may also be substituted for the Phos hilaron at Evening Prayer (BCP, pp. 64, 118). In An Order for Service for Noonday, the office hymn immediately follows the opening preces (BCP, p. 103). At Compline the office hymn follows the short lesson (BCP, p. 132).
Glossary definitions provided courtesy of Church Publishing Incorporated, New York, NY,(All Rights reserved) from "An Episcopal Dictionary of the Church, A User Friendly Reference for Episcopalians," Don S. Armentrout and Robert Boak Slocum, editors.