Today is the first day of the Easter Triduum.

In the Middle Ages, specifically in England, the Mass was performed with a greater solemnity than during the rest of the liturgical year. The priest consecrated three hosts: one for his communion at the Mass, one for his communion at the Good Friday Mass, and a third to be used in sepulchre ceremonies. When Maundy Thursday Mass was complete, the altars of the church were ritually stripped of their coverings while a series of responsories (chants) about the Passion or the prophets were sung. As each altar was stripped the presiding priest recited a collect to the particular saint to whom the altar was dedicated. After they were stripped, the altars were washed with a mixture of water and wine, and scrubbed using a broom of sharp twigs. Each of these actions were symbolic: the stripping of the altars symbolized the stripping of Jesus for his death, the water and wine were the water and blood from his pierced side, and the sharp twigs were the scourges or the crown of thorns.

In the larger religious houses, these actions were followed by the Maundy - the solemn feet-washing echoing the description of Christ washing the feet of his disciples in the Gospel of John. It is believed, due to lack of description in contemporary accounts, that the Maundy was not regularly observed on Maundy Thursday.

One aspect of regular Mass not observed on Maundy Thursday was the pax because, according to John Mirk's Festial, "Iudas betrayd Crist thys nyght wyth a cosse."