This is certainly a good question. The first reading and the Gospel, it is true, are specifically chosen by the Church because of a connection between the two readings. The same is true of the Psalm, while the second reading (on days on which there is one) is chosen not because of a thematic connection but through a continuous reading of one of the Epistles or letters from the New Testament.

The General Instruction of the Roman Missal (2002) says of the Psalm: "After the first reading comes the responsorial Psalm, which is an integral part of the Liturgy of the Word and holds great liturgical and pastoral importance, because it fosters meditation on the word of the God" (no. 61). The responsorial Psalm is, then, just that: a response to the first reading.

The Instruction goes on to say, "The responsorial Psalm should correspond to each reading and should, as a rule, be taken from the Lectionary. 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" (no. 61).

The responsorial Psalm, then, is not the opportunity for the congregation to see how skilled and talented a singer the cantor is. It is to be a heartfelt response by the people to the Word of God taken from the Word of God. It is a time for prayer and meditation upon the Word just proclaimed.

"In order, however, that the people may be able to sing the Psalm response more readily, texts of some responses and Psalms have been chosen for the various seasons of the year or for the various categories of saints. These may be used in place of the text corresponding to the reading whenever the Psalm is sung. 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" (no. 61).

Accordingly, for the Universal Church, the Psalm may be chosen from one of the Psalms already selected for use in, say, the Easter season or on the Feasts of the Apostles. It should not, however, be replaced with another Psalm that is preferred over the one given in the Lectionary.

However, it should be noted that the Dioceses of the United States have received permission from the Holy See for the following to replace the responsorial Psalm of the day: "either the proper or seasonal antiphon and Psalm from the Lectionary, as found 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" (no. 61).

This clause would seem to say that the Psalm of the day may be replaced with another Psalm for good pastoral reason. Such a reason would certainly include singing a Psalm more suitable to the saint of the day or the liturgical season and if the assembly did not know any musical settings for the given Psalm. However, when choosing another Psalm every effort should be taken to select another Psalm whose text corresponds to the Psalm being replaced. I would suggest it does not allow for the changing of a Psalm simply because the cantor prefers another. The Psalms, it should be remembered, are often marvelous places from which to draw a homily and much reflection.

I hope this helps, Matt!

Peace and Joy,

Daren