Liber Usualis

The Liber Usualis (Liber Usualis missæ et officii pro Dominicis et festis cum cantu Gregoriano or "Book for Use at Masses and Offices of Sundays and Feasts with their Gregorian Chants") is a liturgical book of commonly used Gregorian chants in the Catholic tradition, compiled by the monks of the Abbey of Solesmes in France and first published in 1898. It gathered between two covers the ordinary and proper chants from the Kyriale and Graduale needed for Masses of Sunday and important Holy Days; those for Vespers from the Antiphonale; and Matins of Christmas, Holy Week and the Office of the Dead from the Nocturnale. Its most important omissions are the chants for the weekdays of Lent and the Ember Days.

The Liber was first edited in 1896 by Solesmes Abbot Dom André Mocquereau (1849–1930). Its use has decreased since the Second Vatican Ecumenical Council (opened by Pope John XXIII in 1962), where the constitution on the liturgy (Sacrosanctum Concilium) replaced (from Advent 1969) the Tridentine Mass with the Novus ordo and the Divine Office with a drastically revised Liturgy of the Hours. In 1974 a new Graduale Romanum (and in 1990 a Gregorian Missal) appeared in response to the same council's mandate that Gregorian chant should retain "pride of place" in the liturgy (Sacrosanctum Concilium, 116). It resigned the traditional chants according to the new calendar, but introduction of the vernacular has hindered widespread use of Latin chant. The 1964 Liber usualis continues to be used locally where permission exists for celebrations according to the vetus ordo.