The Vigil of St. John the Baptist is of simple rite. The liturgical colour is violet.
The Vigil begins with the Office of Mattins and Lauds. At Mattins the invitatory, hymn, antiphons and psalms are taken from the ferial psalter. The last three psalms, or rather three psalm-fragments, are from 'Feria quarta ad Matutinum, in III Nocturno II'. The lessons for the nocturn are proper to the Vigil and are taken from a homily of St. Ambrose on St. Luke's Gospel. The responsories are taken from the Wednesday after the IV Sunday after Pentecost. At Lauds the second schema is sung (a modified form of the ancient ferial Lauds) with psalms 50, 64, 100, Exsultavit cor meum and 145. The versicle and response after the hymn, and the antiphon on the Benedictus are of the Vigil. After the antiphon on the Benedictus has been repeated the Choir kneels and the ferial preces are sung. Following the preces the collect of the Vigil is sung followed by the Suffrage of the Saints.
At the Hours all is taken from the ferial psalter except the collect which is of the Vigil. At Prime psalm 96, displaced from Lauds, is sung after the psalms of Wednesday. The ferial chapter, Pacem et veritatem, is sung as are the Dominical and ferial preces the Choir kneeling. At the other Little Hours the ferial preces are also sung, kneeling.
Mass is sung after None. The ministers wear dalmatic and tunicle. The Mass is proper with the introit Ne timeas, Zacharia. There is no Gloria. The second collect is of the BVM, Concede nos, the third collect Ecclesiae, for the Church or for the pope. Benedicamus Domino is sung as the dismissal.
After Mass the liturgical colour changes as the great feast of the Forerunner begins with First Vespers.
In the 'liturgical books of 1962' the ferial preces are not sung at Lauds or Little Hours. At Prime the fourth psalm is not added, Pacem et veritatem has been abolished so the formerly feastal Regi saeculorum is sung. The Dominical preces are not sung either. At Mass, sung after Terce, there is only one collect and the dismissal is Ite, missa est.