General Instruction of the Roman Missal: Chapter IV, The Different Forms of Celebrating Mass
III. Mass at Which Only One Minister Participates
252At a Mass celebrated by a priest with only one minister to assist him and to make the responses, the rite of Mass with a congregation is followed (cf. nos. 120-169), the minister saying the people’s parts as appropriate.
253If, however, the minister is a deacon, he performs his proper duties (cf. nos. 171-186) and likewise carries out the other parts, that is, those of the people.
254Mass should not be celebrated without a minister or at least one of the faithful, except for a just and reasonable cause. In this case, the greetings, the introductory or explanatory remarks, and the blessing at the end of Mass are omitted.
255Before Mass, the necessary vessels are prepared either at the credence table or on the righthand side of the altar.
256The priest approaches the altar and, after making a profound bow along with the minister, venerates the altar with a kiss and goes to the chair. If he wishes, the priest may remain at the altar; in this case, the Missal is likewise prepared there. Then the minister or the priest says the Entrance Antiphon.
257Then the priest, standing, makes with the minister the sign of the Cross as the priest says, In nomine Patris (In the name of the Father). Facing the minister, he greets the minister choosing one of the formulas of greeting.
258Then the Act of Penitence takes place, and, if required by the rubrics, the Kyrie and Gloria are said.
259Then, with hands joined, the priest says, Oremus (Let us pray). After a suitable pause, with hands extended he says the collect. At the end the minister makes the acclamation, Amen.
260The readings should whenever possible be proclaimed from the ambo or a lectern.
261After the collect, the minister reads the first reading and Psalm, the second reading, when it is to be said, and the verse for the Alleluia or other chant.
262Then the priest bows profoundly and says the Munda cor meum (Almighty God, cleanse my heart) and, afterwards, reads the Gospel. At the conclusion he says, Verbum Domini (The Gospel of the Lord), to which the minister responds, Laus tibi, Christe (Praise to you, Lord Jesus Christ). The priest then venerates the book with a kiss, saying quietly the Per evangelica dicta (May the words of the Gospel).
263Afterwards, if required by the rubrics, the priest says the Creed together with the minister.
264The Prayer of the Faithful follows, which may be said even in this form of Mass. The priest introduces and concludes it, with the minister announcing the intentions.
265In the Liturgy of the Eucharist, everything is done as in a Mass with a congregation, with the following exceptions.
266After the acclamation at the end of the embolism that follows the Lord’s Prayer, the priest says the prayer Domine Iesu Christe, qui dixisti (Lord Jesus Christ, you said). He then adds, Pax Domini sit semper vobiscum (The peace of the Lord be with you always), and the minister answers, Et cum spiritu tuo (And also with you). The priest gives the sign of peace to the minister, if appropriate.
267Then, while he says the Agnus Dei (Lamb of God) with the minister, the priest breaks the host over the paten. After the Agnus Dei, he performs the commingling, saying quietly the Haec commixtio (May this mingling).
268After the commingling, the priest quietly says the prayer Domine Iesu Christe, Fili Dei vivi (Lord Jesus Christ, Son of the living God) or Perceptio (Lord Jesus Christ, with faith in your love and mercy). Then he genuflects, takes the host, and, if the minister is to receive Communion, turns to the minister and, holding the host a little above the paten or the chalice, says the Ecce Agnus Dei (This is the Lamb of God), adding with the minister the Domine, non sum dignus (Lord, I am not worthy). Facing the altar, the priest then partakes of the Body of Christ. If, however, the minister does not receive Communion, the priest, after genuflecting, takes the host and, facing the altar, says quietly the Domine, non sum dignus (Lord, I am not worthy) and the Corpus Christi custodiat (May the Body of Christ bring) and then receives the Body of Christ. Then he takes the chalice and says quietly, Sanguis Christi custodiat (May the Blood of Christ bring), and then consumes the Blood of Christ.
269Before Communion is given to the minister, the Communion Antiphon is said by the minister or by the priest himself.
270The priest purifies the chalice at the credence table or at the altar. If the chalice is purified at the altar, it may be carried to the credence table by the minister or may again be placed on the altar at the side.
271After the purification of the chalice, the priest should observe some moments of silence, after which he says the prayer after Communion.
272The concluding rites are carried out as at a Mass with a congregation, but the dismissal formula is omitted. The priest venerates the altar in the usual way with a kiss and, after making a profound bow with the minister, departs.