The Master of Ceremonies (MC) at Solemn Mass assists the celebrant, deacon, and acolyte, as necessary, and he assures that the other servers perform their designated duties in an appropriate and timely manner.
The MC also fulfills other crucial functions that the servers cannot when they are occupied with other duties.
Furthermore, the MC is crucial for organizing the servers before mass and restoring order in the chancel and vestry after mass. In a pinch, when the acolyte does not show up or cannot carry out his role, the MC should be ready to take his place. Likewise, if another server fails to appear or cannot serve, the MC is responsible for shuffling duties appropriately and, if necessary, taking himself the role of thurifer, crucifer, or even tapere, if circumstances warrant.
At least 20 minutes before mass, the MC vests in a cassock and assists the acolyte in making sure that the vessels and linens at the credence are arranged properly. He should likewise make sure that the Gospel is marked in the evangeliary, that the lectionary is open to the First Reading, and that the ribbons are in the right places in the altar missal.
With the acolyte, he readies the chancel and sanctuary for mass, setting out service leaflets for the ministers and servers, together with a hymnal for the celebrant (with the recessional hymn marked), taking also the processional cross to the vestry, and preparing the thurible, prior to the arrival of the servers.
The MC reviews the order of service with the other servers and briefs them, if necessary, on their respective roles and duties.
With the acolyte, the MC conducts the other servers to the sacristy five minutes before the beginning of mass for the preparatory Prayers before Mass.
For the entrance into the church, the MC joins the processional party behind the crucifer and just ahead of the choir. If there are extra servers, they are in front of the MC.
Arriving at the foot of the altar, he genuflects, and moves to the right near the pavement candle, standing at the ready to receive the birettas of the celebrant and deacon (and subdeacon, if there is one)
The MC sets the birettas in the ministers' seats in the sedilia.
The MC remains on the Epistle-side and follows the thurifer up to the altar in order to hold the missal and missal stand during the censing.
He takes the missal and missal stand from the altar while the thurifer is receiving incense, and stands against the wall close to the credence table facing liturgical North during the censing. He opens the missal to the propers, if that has not already been done by the deacon.
After the censing is done, he returns the missal to the Epistle-side corner, straight with the edges of the altar.
The MC then goes to his place in the Gospel-side, rear choir stall and remains standing.
For the Readings he sits in the Gospel-side, rear choir stall with one of the torch bearers.
When the Gospel Procession is ready to form, the MC moves directly to the footpace on the epistle side. He genuflects with the ministers when they arrive, and then moves up to the altar with the acolyte, and moves the missal and stand from the Epistle-side to the Gospel side, genuflecting again as he does so. The missal should be angled inward while on the Gospel side.
This being done, the MC should move directly off to his place in the Gospel-side choir stall.
During the Gospel Procession and Gospel Proclamation, the MC remains in his pew, turning to face the evangeliary.
He sits at his place on the Gospel side for the homily.
For the Creed, the Petitions, and the Penitential Rite the MC stands/kneels at his place in the Gospel-side, rear choir stall, cueing the proper reverences. At the creed, he leads all the servers in turning toward the altar.
At the announcements, the MC cues the servers to sit when the ministers pass through the chancel.
At the Offertory, the MC cues the mitre and crozier bearers to take the alms basins to the ushers, and he reminds if necessary one of the torch bearers to retrieve the alms basins when the collection is done and the plates are presented at the chancel gate.
He goes to the vestry and lights the communion torches, then returns to his place on the Gospel side.
At the second censing, the MC takes the missal and missal stand from the altar, and holds them, standing back against the gospel side wall. After the altar is censed, he places the missal back on the altar and returns to his place at the altar step.
At the Pray Brethren, he makes sure the torches join the thurifer and go back to the vestry.
During the Preface and Sanctus, as well as throughout the consecration and communion, the MC keeps an eye on the torch bearers and helps assure that they keep their positions properly.
After the celebrant has taken communion, the MC moves to the epistle side and receives the hand paten from the acolyte, and then moves back to the Gospel side for communion. He receives communion from the deacon on the Gospel side.
The MC then stands and assists the deacon as his paten bearer.
After communion, the MC assures that the torch bearers or extra servers open the gates.
During the ablutions, the MC has three or four tasks, which he must do briskly, but in a dignified manner:
If there are concelebrating priests, then the MC first takes the ablution cup, located just inside the door to the sacristy, to the concelebrants at their places in the chancel pews.
He then takes the birettas from the sedilia and sets them just to the left of the bell, together with the celebrant’s hymnal.
At the completion of the ablutions, he immediately steps up to the altar, where he moves the missal and missal stand to the Epistle side at the bidding of the deacon, minding the proper genuflections. He then returns to his place in the choir stall and kneels.
After the Dismissal, the MC makes sure that the recessional party forms properly.
He moves to the Deacon's side and hands the deacon the birettas and hymnal.
When recessional party forms, the MC takes his place behind the celebrant.
For the Recessional, the MC follows the thurifer (now without thurible and behind the crucifer) and walks just ahead of the acolyte.
In the narthex, the MC kneels with the other servers to receive the celebrant’s blessing.
He then assists the acolyte in taking the celebrant’s vestments and carrying them to the sacristy.
In the vestry right after mass, the MC makes sure that the torch bearers extinguish the altar candles in the proper order.
He assists the acolyte in restoring order to the vestry and chancel.