The Vesperal Liturgy of St. Basil the Great: Orthodox Service Books - Number 4

The Divine Liturgy is the primary worship service of the Orthodox Church. The most commonly celebrated forms of the Divine Liturgy are the Liturgy of St. John Chrysostom, the Liturgy of St. Basil, and the Liturgy of the Presanctified Gifts. The Divine Liturgy is a eucharistic service. The Divine Liturgy of St. John Chrysostom, is used on most days of the year, and as a vesperal liturgy on the Annunciation. The Divine Liturgy of St. Basil the Great, is used on the 5 Sundays of Great Lent, and on Saint Basil's feast day (January 1). On the eves of the Nativity and Theophany, and on Holy Thursday (commemorating the Last Supper, the Mystical Supper of Christ with his Disciples) and Great and Holy Saturday (the vesperal vigil for the Feast of Pascha, the Resurrection of Christ) it is celebrated as a vesperal liturgy. All together, St. Basil's liturgy is celebrated 10 times out of the liturgical year.