The Liturgical Year is an annual cycle of seasons and feasts that celebrates the Paschal Mystery, especially focusing on Christ's Death and Resurrection (Easter Cycle), and Birth (Christmas Cycle). The Catechism of the Catholic Church states that "In the Liturgical Year the various aspects of the one Paschal mystery unfold. This is also the case with the cycle of feasts surrounding the mystery of the incarnation (Annunciation, Christmas, Epiphany). They commemorate the beginning of our salvation and communicate to us the first fruits of the Paschal mystery." (CCC 1171)

The celebration of the Liturgical Year is meant to draw the Catholic faithful into the Mystery of Christ, helping them to experience His divine life more fully and deeply. This includes remembering and celebrating the lives of the saints, especially Mary, the Mother of God: "By keeping the memorials of the saints - first of all the holy Mother of God, then the apostles, the martyrs, and other saints - on fixed days of the Liturgical Year, the Church on earth shows that she is united with the liturgy of heaven. She gives glory to Christ for having accomplished his salvation in his glorified members; their example encourages her on her way to the Father." (CCC 1195)

The Western and Eastern rites of the Catholic Church hold the major feast days and seasons in common, but differ on many of the solemnities and feasts. Below are the most important feast days, plus some of the feasts unique to the Eastern Catholic Churches.

2011-2012 Liturgical and Feast Days

In the season of Pentecost
September 1: The Beginning of the Church Year
September 5: Labor Day (USA)
September 8: Nativity of the Mother of God
September 14: Exaltation of the Holy and Life-Giving Cross
October 1: Feast of the Protection of the Most Holy Mother of God
October 10: Columbus Day (USA)
October 16: Sunday of the Fathers of the 7th Ecumenical Council
November 8: Synaxis of the Archangel Michael and the Other Bodiless Powers
November 11: Veterans' Day (USA)

Preparation for the Nativity of Our Lord
November 14: Philip the Apostle
November 15-December 24: St. Philip's Fast
November 21: Entrance of the Mother of God
November 24: Thanksgiving Day (USA)
December 6: Feast of St. Nicholas
December 8: Conception by Anne of the Most Holy Mother of God (Immaculate Conception)
December 11: Second Sunday Before Christmas (Holy Forefathers)
December 12: Our Lady of Guadalupe
December 18: Sunday Before Christmas (Holy Fathers)

Season of the Christmas cycle
*December 24: Eve, Nativity of Our Lord
*December 25: Nativity of Our Lord
December 26: Synaxis of the Mother of God
December 27: Feast of St. Stephen, First Martyr
December 28: 20,000 Martyrs of Nicomedia
December 29: 14,000 Infants (The Holy Innocents) Slain by Herod at Bethlehem
January 1: Circumcision of our Lord
*January 6: Baptism of our Lord
January 8: Sunday after Theophany

Pre-Paschal season
January 22: Sunday of Zaccheus
January 29: Sunday of the Publican and Pharisee
January 30: Three Great Hierarchs
February 2: Encounter of our Lord with Simeon
February 5: Sunday of Prodigal Son
February 11: First All-Souls Saturday
February 12: Meat-fare Sunday
February 19: Cheese-fare Sunday
February 20: Great Fast (Lent) begins

Sundays of Great Lent
February 26: First Sunday of Lent
March 3: Second All-Souls Saturday
March 4: Second Sunday of Lent
March 11: Third Sunday of Lent (Veneration of the Cross)
March 18: Fourth Sunday of Lent
*March 25: Annunciation of the Mother of God

Holy Week
March 31-April 8: Great and Holy Week
March 31: Lazarus Saturday
April 1: Palm (Flowery) Sunday - Entrance into Jerusalem
April 2: Great and Holy Monday
April 3: Great and Holy Tuesday
April 4: Great and Holy Wednesday
April 5: Great and Holy Thursday
April 6: Great and Holy Friday
April 7: Great and Holy Saturday
April 8: Easter Sunday, begins Season of Pentecost

Paschal Season
April 8-15: Bright Week
April 9: Bright Monday
April 15: Second Sunday of Pascha (Apostle Thomas)
April 22: Third Sunday of Pascha (Ointment-Bearing Women)
April 23: Feast of George, Great Martyr
April 29: Fourth Sunday of Pascha (Healing of the Paralytic)
May 2: Mid Pentecost (Wednesday)
May 6: Fifth Sunday of Pascha (Samaritan Woman)
May 11: Feast of Saints Cyril & Methodius
May 13: Sixth Sunday Sunday of Pascha (Man Born Blind)
*May 17: Ascension of Our Lord, Thursday (40 days after Easter)
May 20: Seventh Sunday of Pascha (Fathers of the First Council)
May 27: Feast of Pentecost Pentecost Sunday (50 days after Easter)
May 28: Memorial Day (USA)
June 3: 1st Sunday after Pentecost Sunday of All Saints

Continuing in the Season of Pentecost
June 24: The Birth of John the Baptist
*June 29: Feast of SS Peter and Paul, Apostles
July 4: Independence Day (USA)
July 20: Feast of the Holy Prophet Elias
August 6: Transfiguration of Our Lord
*August 15: Dormition of the Mother of God
August 29: Beheading of John the Baptist

For a history and detailed explanation of the Christian liturgical calendar, see the "Christian Calendar" entry in the Catholic Encyclopedia.