The Vigil of the Nativity of St. John the Baptist is of simple rite and the liturgical colour of the day is violet.
The Office begins with Mattins. The invitatory, hymn, the six antiphons and psalms of the nocturn are of the feria (Pss. 52, 54, 55, 56, 57, 58, 59, 60, 61, 63, 65 & 67). The lessons in the nocturn are a homily on St. Luke's Gospel of St. Ambrose. The lessons are the same as those found in the modern editions except the first lesson ends ...inter superiores semine rather than ...inter superiores familias. The three responsories are taken from the occurring feria. Lauds follow the third responsory. The ferial psalter is sung (Pss. 50, 64, 62-66, Exsultavit cor meum & 148-149-150). The chapter, hymn, V&R and antiphon on the Benedictus are from the feria. After the antiphon on the Benedictus has been sung in full at the end of the canticle the ferial preces are sung, kneeling, including the psalm De profundis. The collect is proper to the Vigil. After the collect of the Vigil the Suffrages are sung.
At Prime the antiphons of the feria are sung with psalms 53, 25, 118i & 118ii. Both the Dominical and ferial preces are sung. The ferial preces are sung at the other Horae Minores.
Mass is sung after None. The ministers wear violet dalmatic and tunicle. The Mass formulary is proper Ne timeas etc. There is no Gloria, the second collect is of the BVM, the third for the Church. Benedicamus Domino is sung as the dismissal.