missal,type of book containing the prayers, important chants, and necessary instructions for the celebration of the mass (Latin: missa) in the Roman Catholic church throughout the year.

The missal developed from various books used in the early church, for by the 5th century a separate mass book had been developed for the use of each participant in the liturgy. The priest at the altar, for instance, used the sacramentary, a book containing the orations and prefaces that vary from feast to feast. The fixed prayers that form the ordinary of the mass were contained in the sacramentary. For Scripture readings, a Bible with marked passages had originally been used, but after about 1000, a special book, the lectionary, was developed that contained only the Epistles and Gospels to be read at each feast. The soloist who led the congregation in responsive singing of the Psalms used a book called the cantatorium. The chants to be sung by the choir were contained in the antiphonary. Finally, a separate book, the ordo (Ordines Romani), gave the directions for the proper carrying out of the liturgical functions.

All these books were gradually combined into one volume, the Missale plenum (“full missal”), which by the 13th century had replaced the older books. All modern missals are of this type. The Missale plenum existed in various forms; the most popular was the missal of the Roman Curia, which had evidently developed primarily during the time of Pope Innocent III (1198–1216). This missal was adopted by the Franciscan friars and spread by them throughout Europe.

The Council of Trent (1545–63) proposed that the Roman liturgy be reformed, and in 1570 Pope Pius V promulgated a new missal, which was adopted throughout the Latin rite. This missal was frequently, though not radically, revised. The influential liturgical movement in the 20th century was influential and led to the revision of the liturgy of Holy Week under Pius XII in 1955 and culminated in the decree of the second Second Vatican Council (1963) that allowed the introduction of the vernacular in the variable parts of the liturgy and ordered a complete revision of the missal to be carried out by a postconciliar commission. The revised missal, issued in 1970, consists of two volumes: one containing the order of the mass and the other a lectionary of Scripture readings covering a three-year cycle.

The Eastern church has never adopted one book to be used by the celebrant of the liturgy. The Anthologion, an Eastern book similar to the Western missal, was used by some beginning in the 13th century, and an edition was published in Athens as late as 1882. Small hand missals are commonly used by the worshipers in the Eastern church.