Excerpts from the General Instruction of the Roman Missal (GIRM, 2002)
The Importance of Singing
39. The Christian faithful who gather together as one to await the Lord's coming are instructed by the Apostle Paul to sing together psalms, hymns, and spiritual songs (cf. Col 3:16). Singing is the sign of the heart's joy (cf. Acts 2:46). Thus Saint Augustine says rightly, "Singing is for one who loves." There is also the ancient proverb: "One who sings well prays twice."
40. Great importance should therefore be attached to the use of singing in the celebration of the Mass, with due consideration for the culture of the people and abilities of each liturgical assembly. Although it is not always necessary (e.g., in weekday Masses) to sing all the texts that are of themselves meant to be sung, every care should be taken that singing by the ministers and the people is not absent in celebrations that occur on Sundays and on holy days of obligation.
In the choosing of the parts actually to be sung, however, preference should be given to those that are of greater importance and especially to those to be sung by the priest or the deacon or the lector, with the people responding, or by the priest and people together. [cf Musicam sacram, nos. 7,16]
41. All other things being equal, Gregorian chant holds pride of place because it is proper to the Roman Liturgy. Other types of sacred music, in particular polyphony, are in no way excluded, provided that they correspond to the spirit of the liturgical action and that they foster the participation of all the faithful. [SC 116]
Since faithful from different countries come together ever more frequently, it is fitting that they know how to sing together at least some parts of the Ordinary of the Mass in Latin, especially the Creed and the Lord's Prayer, set to the simpler melodies. [SC 54]
Entrance Chant
47. After the people have gathered, the Entrance chant begins as the priest enters with the deacon and ministers. The purpose of this chant is to open the celebration, foster the unity of those who have been gathered, introduce their thoughts to the mystery of the liturgical season or festivity, and accompany the procession of the priest and ministers.
48. The singing at this time is done either alternately by the choir and the people or in a similar way by the cantor and the people, or entirely by the people, or by the choir alone. In the dioceses of the United States of America there are four options for the Entrance Chant: (1) the antiphon from the Roman Missal or the Psalm from the Roman Gradual as set to music there or in another musical setting; (2) the seasonal antiphon and Psalm of the Simple Gradual; (3) a song from another collection of psalms and antiphons, approved by the Conference of Bishops or the Diocesan Bishop, including psalms arranged in responsorial or metrical forms; (4) a suitable liturgical song similarly approved by the Conference of Bishops or the Diocesan Bishop.
If there is no singing at the entrance, the antiphon in the Missal is recited either by the faithful, or by some of them, or by a lector; otherwise, it is recited by the priest himself, who may even adapt it as an introductory explanation. (Note: see also Communion Chant, in paragraph #87)
The Responsorial Psalm
61. …It is preferable that the responsorial Psalm be sung, at least as far as the people's response is concerned. Hence, the psalmist, or the cantor of the Psalm, sings the verses of the Psalm from the ambo or another suitable place. The entire congregation remains seated and listens but, as a rule, takes part by singing the response, except when the Psalm is sung straight through without a response… If the Psalm cannot be sung, then it should be recited in such a way that it is particularly suited to fostering meditation on the word of God.
In the dioceses of the United States of America, the following may also be sung in place of the Psalm assigned in the Lectionary for Mass: either the proper or seasonal antiphon and Psalm from the Lectionary, as found either in the Roman Gradual or Simple Gradual or in another musical setting; or an antiphon and Psalm from another collection of the psalms and antiphons, including psalms arranged in metrical form, providing that they have been approved by the United States Conference of Catholic Bishops or the Diocesan Bishop. Songs or hymns may not be used in place of the responsorial Psalm.
Gospel Acclamation
62. After the reading that immediately precedes the Gospel, the Alleluia or another chant indicated by the rubrics is sung, as required by the liturgical season. …It is sung by all while standing and is led by the choir or a cantor, being repeated if this is appropriate. The verse, however, is sung either by the choir or by the cantor.
During Lent, in place of the Alleluia, the verse before the Gospel is sung, as indicated in the Lectionary. It is also permissible to sing another psalm or tract, as found in the Graduale….
The Alleluia or verse before the Gospel may be omitted if they are not sung.
64. The Sequence, which is optional except on Easter Sunday and on Pentecost Day, is sung before the Alleluia.
The Profession of Faith
68. The Creed is to be sung or said by the priest together with the people on Sundays and Solemnities…If it is sung, it is begun by the priest or, if this is appropriate, by a cantor or by the choir. It is sung, however, either by all together or by the people alternating with the choir. If not sung, it is to be recited by all together or by two parts of the assembly responding one to the other.
Offertory chant
74. The procession bringing the gifts is accompanied by the Offertory chant (cf. above, no. 37b), which continues at least until the gifts have been placed on the altar. The norms on the manner of singing are the same as for the Entrance chant (cf. above, no. 48). Singing may always accompany the rite at the offertory, even when there is no procession with the gifts.
