In the local Church, first place should certainly be given, because of its significance, to the Mass at which the Bishop presides, surrounded by his presbyterate, deacons, and lay ministers,91Cf. Second Vatican Ecumenical Council, Constitution on the Sacred Liturgy, Sacrosanctum Concilium, no. 41. and in which the holy people of God participate fully and actively, for it is there that the preeminent expression of the Church is found. At a Mass celebrated by the Bishop or at which he presides without celebrating the Eucharist, the norms found in the Caeremoniale Episcoporum should be observed.92Cf. Caeremoniale Episcoporum, editio typica, 1984, nos. 119-186
Great importance should also be attached to a Mass celebrated with any community, but especially with the parish community, inasmuch as it represents the universal Church gathered at a given time and place. This is particularly true in the communal Sunday celebration.93Cf. Second Vatican Ecumenical Council, Constitution on the Sacred Liturgy, Sacrosanctum Concilium, no. 42; Dogmatic Constitution on the Church, Lumen gentium, no. 28; Decree on the Ministry and Life of Priests, Presbyterorum ordinis, no. 5; Sacred Congregation of Rites, Instruction Eucharisticum mysterium, On the worship of the Eucharist, 25 May 1967, no. 26: AAS 59 (1967), p. 555.
Among those Masses celebrated by some communities, moreover, the conventual Mass, which is a part of the daily Office, or the community Mass, has a particular place. Although such Masses do not have a special form of celebration, it is nevertheless most proper that they be celebrated with singing, especially with the full participation of all members of the community, whether of religious or of canons. In these Masses, therefore, individuals should exercise the office proper to the Order or ministry they have received. It is appropriate, therefore, that all the priests who are not bound to celebrate individually for the pastoral benefit of the faithful concelebrate at the conventual or community Mass in so far as it is possible. In addition, all priests belonging to the community who are obliged, as a matter of duty, to celebrate individually for the pastoral benefit of the faithful may also on the same day concelebrate at the conventual or community Mass.94Cf. Sacred Congregation of Rites, Instruction Eucharisticum mysterium, On the worship of the Eucharist, 25 May 1967, no. 47: AAS 59 (1967), p. 565. For it is preferable that priests who are present at a Eucharistic Celebration, unless excused for a good reason, should as a rule exercise the office proper to their Order and hence take part as concelebrants, wearing the sacred vestments. Otherwise, they wear their proper choir dress or a surplice over a cassock.