The ecclesiastical year, which begins on the first of September, is divided between movable and immovable or fixed holy days. The movable holy days are determined by the date of Easter, the most important of all feast days. Next in importance to Easter are the "twelve great feasts," of which three are movable. Eight of these feasts are devoted to Christ and four to the Virgin Mary. There are also a number of feast days of varying importance, most of which commemorate the more popular saints.

The "twelve great feasts," as they occur in chronological order after September 1, are:

The Nativity of the Virgin Mary (September 8)
The Elevation of the Life-giving Cross (September 14)
The Presentation of the Virgin Mary in the Temple (November 21)
Christmas (December 25)
Epiphany (January 6)
The Presentation of Christ in the Temple (February 2)
The Annunciation (March 25)
Palm Sunday (the Sunday before Easter)
The Ascension (40 days after Easter)
Pentecost (50 days after Easter)
The Transfiguration (August 6)
The Repose of the Virgin Mary (August 15)

The above information was provided courtesy of the Greek Orthodox Archdiocese of America.