The calendar of saints is a traditional Christian method of organising a liturgical year on the level of days by associating each day with a saint, and referring to the day as the saint's day of that saint. This calendar system, when combined with major church festivals and movable and immovable feasts, constructs a very human and personalised yet often localised way of organising the year and identifying dates. It may be compared with the Roman Missal.

Various feast days will be "ranked" with various levels of importance. In the Roman Catholic Church, from most to least importance, these are solemnities, feasts, memorials, and optional memorials. The rankings listed below are those for the universal church, various countries or dioceses may have additional saints or blessed's in their calendars. If no ranking is given, the feast day belongs to some particular calendar and not the universal calendar.

There are thousands of canonized saints, that is those individuals officially recognized by the Church as holy men and women worthy of imitation. Because miracles have been associated with these people, and their lives have been fully examined and found holy by the Church, we can be assured they are prime examples of holiness, and powerful intercessors before God on our behalf. There are also many patron saints, guardians or protectors of different areas and states of life. For instance, St. Vitus is the patron saint against oversleeping, and St. Joseph of Cupertino is the patron saint of air travelers. It may sound crazy to have a patron saint against oversleeping, but keep in mind the Church has something meaningful for every area of our human lives. All of these saints are celebrated throughout the year, as many have their own feast days 

The Tridentine Missal has common formulas for Masses of Martyrs, Confessors who were bishops, Doctors of the Church, Confessors who were not Bishops, Abbots, Virgins, Non-Virgins, Dedication of Churches, and Feast Days of the Blessed Virgin Mary. Pope Pius XII added a common formula for Popes. The 1962 Roman Missal of Pope John XXIII omitted the common of Apostles, assigning a proper Mass to every feast day of an Apostle. The present Roman Missal has common formulas for the Dedication of Churches, the Blessed Virgin Mary, Martyrs (with special formulas for missionary martyrs and virgin martyrs), Pastors (subdivided into bishops, generic pastors, founders of churches, and missionaries), Doctors of the Church, Virgins, and (generic) Saints (with special formulas for abbots, monks, nuns, religious, those noted for works of mercy, educators, and [generically] women saints).

As the number of recognized saints increased during Late Antiquity and the first half of the Middle Ages, eventually every day of the year had at least one saint who was commemorated on that date. To deal with this increase, some saints were moved to alternate days in some traditions or completely removed, with the result that some saints have more than one feast day.The General Roman Calendar, in its various forms, contains only a selection of the saints for each of its days. 

Each month of the year is dedicated to a particular devotion within the Catholic faith; the dedication of each month is based on historical events or a particular aspect of the liturgical calendar, or a combination of the two. These monthly Catholic devotions do not line up exactly with the time frame of the liturgical calendar, since they are fixed to standard calendar months rather than the Church seasons. Some countries and areas have developed monthly dedications to devotions more specific to their area, but the following are the common, widespread Catholic devotions for each month throughout the year.

January : Month of the Holy Name
January is the month of the Holy Name of Jesus. The feast of the Holy Name originated in the 1500s and was formerly celebrated on the second Sunday of Epiphany. It was removed from the calendar in 1969, "since the imposition of the name of Jesus is already commemorated in the office of the Octave of Christmas." (motu propri: Mysterii Paschalis, 1969) It was restored in 2002 as an optional memorial on the first free day after January 1st.

Because of the feasts in January which pertain to Christ's infancy and childhood, January has also become a month dedicated to the Holy Childhood of Jesus.

February : Month of the Passion of Our Lord
February is the month dedicated to the Holy Family. Though the start of the Lenten season changes within the calendar year, a fair-sized portion of February gives us a space of time between the Christmas celebrations and the increased focus on Jesus's public life and ministry, which occurs in Lent. It is a transition from the feast of Christmas to the fasting of Lent. Therefore traditionally February has become a time to recall the Holy Family; within the Holy Family is where Jesus spent the time between his birth and embarking on his public journey.

March : Month of St. Joseph
March is the month of devotion to St. Joseph, whose feast falls on March 19th. The date of the solemnity of St. Joseph dates to the end of the 15th century; within the next few centuries, the entire month as a time for devotion to St. Joseph became part of tradition.

In a society which seems to discourage the importance of marriage and fatherhood, St. Joseph, the spouse of the Virgin and the man given the responsibility of raising Jesus, is an incredible model of an obedient, faithful, Christian father. 

April : Month of the Holy Eucharist
The month of April is dedicated both to devotion to the Eucharist and devotion to the Holy Spirit. This tradition has developed because Easter Sunday often falls in April, and when it does fall in March, the Easter season continues on through all of April. In essence, April is a month of Easter, and during the Easter celebration we remember the Eucharistic sacrifice Christ gave us and the baptism in the Holy Spirit, which would come after Jesus's resurrection.

May : Month of Our Lady
May is the month of Mary; devotion to the Blessed Mother throughout May originated in Rome in the 18th century to counter immorality and infidelity among students at a college there. It has spread through most of the Latin Church now. Because the North American holiday of Mother's Day falls in May, Catholics take this time to recall and try to emulate Mary's role as mother. Therefore devotion to Mary in the month of May focuses both on Mary as a role model for Christian mothers, and Mary's ever lasting chastity and purity, and her fidelity to God's will.

June : Month of the Sacred Heart
June is the month of the Sacred Heart. A devotion long practiced privately, it was officially approved in the 1800s. Devotion the Sacred Heart encourages participation in Holy Hour Eucharistic Adoration and to receive Holy Communion on the first Friday of every month.

July : Month of the Most Precious Blood
The month of July is dedicated to the Precious Blood. The feast of the Precious Blood of our Lord was instituted in 1849 by Pius IX, but the devotion is as old as Christianity. The early Fathers say that the Church was born from the pierced side of Christ, and that the sacraments were brought forth through His Blood.

"The Precious Blood which we worship is the Blood which the Savior shed for us on Calvary and reassumed at His glorious Resurrection; it is the Blood which courses through the veins of His risen, glorified, living body at the right hand of God the Father in heaven; it is the Blood made present on our altars by the words of Consecration; it is the Blood which merited sanctifying grace for us and through it washes and beautifies our soul and inaugurates the beginning of eternal life in it."

August : Month of the Immaculate Heart of Mary
The month of August is dedicated to the Blessed Sacrament, and increased adoration of the Eucharist is encouraged. August is also dedicated to the Immaculate Heart of Mary, and on August 15th, the church celebrates the Assumption of Mary into heaven.

September : Month of Our Lady of Sorrows
September is traditionally dedicated to the Seven Sorrows (or Dolours) of Mary, and the Feast of Our Lady of Sorrows falls in September. The Sorrows are:the prophecy of Simeon, the flight into Egypt, the loss of the Holy Child at Jerusalemfor three days, meeting Jesus on his way to Calvary, standing at the foot of the Cross, Jesus being taken from the Cross, and the burial of Christ.

October : Month of the Most Holy Rosary
October is the month of the Rosary, because of the anniversary of victory at the Battle at Lepanto and the feast of Our Lady of the Rosary occurring in October. The Battle of Lepanto and the institution of the feast day took place in the 17th century; in the late 1800s, Pope Leo XIII officially dedicated the entire month to devotion to the Holy Rosary.

November : Month of the Holy Souls
The month of November is dedicated to the poor souls in purgatory. All souls day falls on November 2nd, which is when we commemorate all the faithful departed. The indulgences attached to this devotion are seven years and seven quarantines each day; plenary indulgence on any day of the month under the usual conditions.

December : Month of the Divine Infancy
December is dedicated to Advent and the coming of Christ. This refers to the preparation for the celebration of remembering Christ's birth 2000 years ago, but also the prayerful, spiritual preparation for the second and final coming of the Lord.