Violet (Office) and White (Mass)
Also called Maundy Thursday, because of the Mandatum
The Triduum Sacrum begins, comprising Thursday through Saturday
The blessing of meals today is: Christus factus est pro nobis obediens usque ad mortem. (Cf. reliqua in Benedictio mensae, in either the Rituale Romanum or in the appendix of the Breviary)
The principal elements of the evening Mass in Cena Domini:
The liturgical color is white. The altar cross is covered in white for the Mass only; the rest of the day it is covered in violet.
The altar and sanctuary are decorated well, representing the cœnaculum, including floral arrangements and the better vestments, altarware, carpets, etc. The altar cross is covered in white.
The altar of repose, or Sepulchre, is also sumptuously prepared in another location. It must have at least four wax candles burning when the Blessed Sacrament is adored there, but many more are customarily used; one vigil lamp is sufficient after midnight. The location of the Sepulchre and the tabernacle within it must be secure. (Where this is not possible, after the adoration at the Sepulchre closes, the Blessed Sacrament should be moved to a secure location for the night, such as a fixed tabernacle or safe, to be returned to the Sepulchre again on Good Friday morning.)
Before the Mass in Cena Domini, the Blessed Sacrament which is reserved in the main tabernacle is taken to the Sepulchre or to another secure and dignified custodial so that the main altar tabernacle is empty at the beginning of the Mass. It is necessary and important to plan ahead so as to have ciboria prepared to consecrate at the Mass in Cena Domini in enough quantity to distribute Holy Communion on both Maundy Thursday evening and on Good Friday afternoon.
The washing of the feet is an optional rite which may be done after the sermon, with its own particular rubrics as given in the Missal (originally it was a cathedral ceremony and consisted of its own liturgy separate from the Mass).
At the conclusion of the Mass, the Blessed Sacrament is taken ceremonially in procession to the Sepulchre, while Pange lingua is sung, concluded by Tantum ergo and the usual incensation. Adoration continues there for the night, at least until midnight if possible (fit publica adoratio, protrahenda saltem usque ad mediam noctem).
Following the reposition of the Blessed Sacrament at the Sepulchre, the stripping of the altars is done ceremonially; the rubrics are given in the Missal. The altar candles are extinguished beforehand. Everything is removed except the altar cross and candlesticks. The celebrant wears only amice, alb, cincture, and violet stole.
After the Mass, holy water is removed from the stoups at the church doors, which remain empty until after the blessing of the font at the Easter Vigil.
There are some modifications to the rite of Mass:
The prayers at the foot of the altar are modified for Passiontide (the psalm Iudica me is omitted, the rest retained). Likewise, the Gloria Patri is omitted in the Introit and after the Lavabo psalm.
The Gloria is used in the Mass, but not the Credo.
The organ may play up to and including the Gloria, after which it ceases its sound and may play again starting with the Gloria of the Easter Vigil. Bells are also rung at the Gloria, after which all bells must be silent until the Gloria of the Easter Vigil; a clapper is used in their place. When the bells are rung at the Gloria, servers may ring all the sets of altar bells in unison, while the tower bells also peal.
The preface is that of the Holy Cross.
There are proper forms of not only the Communicantes and Hanc igitur, but also of the Qui pridie.
The third response in the Agnus Dei is miserere nobis instead of dona nobis pacem.
The Pax is not given, and the first of the celebrant’s three prayers before Communion is omitted (Domine Iesu Christe qui dixisti).
After Holy Communion is distributed, the ciboria remain on the corporal and Mass continues with the rubrics coram Sanctissimo.
Benedicamus Domino is sung in lieu of Ite missa est. The final blessing and the Last Gospel are omitted.
The rubrics for the procession to the Sepulchre and the subsequent Stripping of the Altars are given in the Missal.
It is a custom in some places that the altar, having been stripped, is washed with water infused with a small quantity of white wine on Thursday night or Friday morning.
The Office is all proper. The altar is vested in violet for the Office. The Gloria Patri is omitted after the psalms. The hours contain the concluding antiphon Christus factus est pro nobis obediens usque ad mortem. Vespers are not said by those who attend the Mass in Cena Domini.
Tenebrae: Matins and Lauds chanted together, with the extinguishing of the candles on the fifteen-candle hearse, per the rubrics.
Matins: No invitatorium or hymn. It begins absolutely with the first antiphon and contains 3 nocturns. If separated from Lauds, add oration Respice quaesumus Domine. No Te Deum.
Lauds: All proper as indicated in the breviary.
Prime: All proper as indicated in the breviary; the martyrology and chapter portion are omitted.
Hours: All proper as indicated in the breviary.
Vespers: Vespers are not said by those who attend the Mass in Cena Domini. Otherwise: All as indicated in the breviary, which borrows the vesperal office from Holy Saturday except for Antiphon 1 and the Magnificat antiphon.
Compline: In common, compline is said after the stripping of the altars. All proper as indicated in the breviary. The beginning and end are abbreviated.