Advent is the preparation for the feast of the birth of Jesus. It cannot have existed before the feast of Christmas was celebrated records of which date from the 4^th Century. The oldest record of a feast of Christ's Nativity occurs in a Roman almanac (the Chronographer of 354, or Philocalian Calendar), which indicates that the festival was observed by the church in Rome by the year 336. The Acts of a synod held at Saragossa in 380, include a canon prescribing that from the seventeenth of December to the feast of the Epiphany no one should be permitted to absent himself from church. The name Advent is first encountered connected with St. Maximus, Bishop of Turin (415-466), who wrote two sermons titled "In Adventu Domini", but he makes no reference to a special time. It is possible that this title was added by a later copyist. Hard evidence for the celebration of Advent begins in the 6^th Century. Sermons probably written by St. Caesarius, Bishop of Arles (502-542) mention a preparation before the birthday of Christ. The collection of sermons of St. Gregory the Great (590-604) begins with one for the second Sunday of Advent.

Advent may have begun as a fast like lent rather than the celebration that it is now. Bishop Perpetuus of Tours (reigned 461-490) initiated a fast before Christmas, beginning from St. Martin's Day on November 11. Known as St. Martin's Lent, the custom was extended to other Frankish churches by the Council of Mâcon in 581.

The 9^th canon of this synod orders that from the eleventh of November to the Nativity the Sacrifice be offered according to the Lenten rite on Monday, Wednesday, and Friday of the week. The Gelasian Sacramentary notes five Sundays for the season; these five were reduced to four by Pope St. Gregory VII (1073-85). In 650 Advent was celebrated in Spain with five Sundays. Several synods had made laws about fasting to be observed during this time, some beginning with the eleventh of November, others the fifteenth, and others as early as the autumnal equinox. Other synods forbade the celebration of matrimony. Advent never assumed the same importance in the Eastern Church as it has in the West. In the Greek Church we find no documents for the observance of Advent earlier than the eighth century. St. Theodore the Studite (d. 826), who speaks of the feasts and fasts commonly celebrated by the Greeks, makes no mention of this season.