What happens at Mass?

A Catholic Mass moves through four parts. The Introductory Rites gather the people and prepare them. The Liturgy of the Word proclaims Scripture and answers it with the homily, the Creed and prayers for the world. The Liturgy of the Eucharist brings bread and wine to the altar, gives thanks over them in the words of Christ at the Last Supper, and shares them in Holy Communion. The Concluding Rites bless the people and send them out.

A Sunday Mass usually takes an hour, a weekday Mass about half that. The shape has been the same since at least the year 155, when a Christian in Rome described it for the emperor. This guide walks through each part and ends with advice for newcomers.

What is the Mass?

The Mass is the Catholic celebration of the Eucharist. It is at once the memorial of Christ's sacrifice on the cross, made present on the altar, and the sacred meal in which Catholics receive his body and blood. The name comes from the Latin dismissal at the end, Ite, missa est.

The Catechism holds the two sides together: "The Mass is at the same time, and inseparably, the sacrificial memorial in which the sacrifice of the cross is perpetuated and the sacred banquet of communion with the Lord's body and blood" (CCC 1382). Our guide to the Eucharist covers that belief; this post covers what you will see and hear.

It is called Holy Mass "because the liturgy in which the mystery of salvation is accomplished concludes with the sending forth (missio) of the faithful, so that they may fulfill God's will in their daily lives" (CCC 1332).

What are the parts of the Mass?

The Mass has two main parts, the Liturgy of the Word and the Liturgy of the Eucharist, framed by rites that open and close the celebration. The Church counts four in all: Introductory Rites, Liturgy of the Word, Liturgy of the Eucharist and Concluding Rites. The two central parts are so joined that they form a single act of worship.

The General Instruction of the Roman Missal, the Church's rulebook for the Mass, says the two parts "are so closely interconnected that they form but one single act of worship" (GIRM 28). The phrase comes from the Second Vatican Council, which asked pastors to teach the faithful "to take their part in the entire Mass" (Sacrosanctum Concilium, 56).

The Catechism says: "The Eucharistic table set for us is the table both of the Word of God and of the Body of the Lord" (CCC 1346). Then it points to the road to Emmaus, where the risen Jesus explained the Scriptures and then sat at table: "he took the bread and blessed, and broke it, and gave it to them. And their eyes were opened and they recognized him" (Luke 24:30-31). Word first, then bread. Every Mass follows that order.

Around the year 155 St. Justin Martyr wrote to the emperor: "On the day we call the day of the sun, all who dwell in the city or country gather in the same place. The memoirs of the apostles and the writings of the prophets are read, as much as time permits." The Catechism says these basic lines "have stayed the same until our own day for all the great liturgical families" (CCC 1345).

What happens in the Introductory Rites?

The Introductory Rites gather a crowd of individuals into one worshipping body. They include the entrance chant and procession, the sign of the cross and greeting, the Penitential Act, the Kyrie, the Gloria on Sundays outside Advent and Lent, and the opening prayer called the collect. They are a beginning, not the main event.

The General Instruction says these rites "have the character of a beginning, introduction, and preparation" (GIRM 46). After the entrance chant the priest kisses the altar, makes the sign of the cross with everyone and greets the people.

In the Penitential Act, after a short silence, "the entire community carries out" a general confession, often the Confiteor. The priest then asks God's mercy, but that prayer "lacks the efficacy of the Sacrament of Penance" (GIRM 51). Serious sin still needs confession. The Kyrie follows, and on Sundays and feasts the Gloria, "a very ancient and venerable hymn" (GIRM 53).

The rites close with the collect, after a silence in which everyone may "formulate their petitions mentally" (GIRM 54). Behind all of it stands the one who presides invisibly: "At its head is Christ himself, the principal agent of the Eucharist" (CCC 1348).

What happens in the Liturgy of the Word?

In the Liturgy of the Word, God speaks to his people through Scripture and they answer. On Sundays there are three readings, from the Old Testament, a New Testament letter and the Gospel. The homily explains the readings, the Creed answers them, and the Prayer of the Faithful brings the needs of the world to God.

The General Instruction summarises the part: "in the readings, as explained by the homily, God speaks to his people," and "Christ himself is present in the midst of the faithful through his word" (GIRM 55).

The Gospel is "the high point of the Liturgy of the Word." The people stand for it, sing the Alleluia before it, and "through their acclamations acknowledge and confess Christ present and speaking to them" (GIRM 60). The same texts serve well for lectio divina during the week.

The homily "is part of the Liturgy and is strongly recommended" (GIRM 65). On Sundays and solemnities the Creed follows, and in the Prayer of the Faithful the people, "exercising the office of their baptismal priesthood, offer prayers to God for the salvation of all" (GIRM 69).

What happens in the Liturgy of the Eucharist?

Bread and wine are brought to the altar, the priest prays the Eucharistic Prayer over them, and by the words of Christ and the power of the Holy Spirit they become his body and blood. This is the centre of the Mass. It does what Jesus did at the Last Supper and told his apostles to repeat.

It begins simply: "At the beginning of the Liturgy of the Eucharist the gifts, which will become Christ's Body and Blood, are brought to the altar" (GIRM 73). The collection belongs here too; from the beginning Christians brought "gifts to share with those in need" along with the bread and wine (CCC 1351).

Then the dialogue begins: "Lift up your hearts. Let us give thanks to the Lord our God." The General Instruction announces the moment: "Now the center and summit of the entire celebration begins: namely, the Eucharistic Prayer, that is, the prayer of thanksgiving and sanctification" (GIRM 78). In the epiclesis the Church asks the Father to send the Holy Spirit on the bread and wine. In the institution narrative the priest repeats the words of Jesus, and "the power of the words and the action of Christ, and the power of the Holy Spirit, make sacramentally present under the species of bread and wine Christ's body and blood, his sacrifice offered on the cross once for all" (CCC 1353).

The words are Christ's own: "This is my body which is given for you. Do this in remembrance of me" (Luke 22:19). Our guide to the seven sacraments explains why Christ himself acts here. After the consecration the Church prays "in communion with the whole Church in heaven and on earth, the living and the dead," naming the Pope and the local bishop (CCC 1354). That is the communion of saints said out loud. The prayer ends with the doxology and the people's "Amen."

What happens at Communion?

The Communion Rite begins with the Our Father and ends with the Prayer after Communion. In between come the sign of peace, the breaking of the bread, the invitation "Behold the Lamb of God," the reply "Lord, I am not worthy," and the procession to receive. Catholics who are prepared receive the body and blood of Christ.

The Catechism describes it in one sentence: "In the communion, preceded by the Lord's prayer and the breaking of the bread, the faithful receive 'the bread of heaven' and 'the cup of salvation,' the body and blood of Christ who offered himself 'for the life of the world'" (CCC 1355). In the Rite of Peace the faithful "express to each other their ecclesial communion and mutual charity" (GIRM 82).

Before receiving, everyone says the words of the centurion: "Lord, I am not worthy that you should enter under my roof, but only say the word and my soul will be healed" (CCC 1386). Communion is received on the tongue or in the hand, with "Amen" as the answer to "The Body of Christ."

Afterwards "the priest and faithful spend some time praying privately" (GIRM 88). "The principal fruit of receiving the Eucharist in Holy Communion is an intimate union with Christ Jesus" (CCC 1391). The Prayer after Communion closes the rite.

What happens in the Concluding Rites?

The Concluding Rites are short: any announcements, the priest's greeting and blessing, the dismissal, and the priest's kiss of the altar as he leaves. The dismissal gives the Mass its name and its purpose. The people are sent out to live what they have received.

The General Instruction lists "The priest's greeting and blessing" and "The dismissal of the people by the deacon or the priest, so that each may go out to do good works, praising and blessing God" (GIRM 90). The deacon or priest says "Go forth, the Mass is ended" or "Go in peace, glorifying the Lord by your life," and the people answer "Thanks be to God."

The Mass does not end at the church door so much as change form. Those who want to keep praying through the day can take up the Liturgy of the Hours.

What should you do if you are new to Mass?

Come early, sit where you can see, and follow the people around you for posture. Say the responses you know and listen to the rest. Anyone may attend. Receiving Communion is for Catholics in a state of grace who have fasted for an hour; everyone else stays in the pew or comes forward for a blessing with arms crossed.

The Church wants more than quiet attendance. The Second Vatican Council "earnestly desires that all the faithful should be led to that fully conscious, and active participation in liturgical celebrations which is demanded by the very nature of the liturgy" (Sacrosanctum Concilium, 14). Standing is for the opening rites, the Gospel, the Creed and the Eucharistic Prayer, sitting for the readings and homily, and in the United States the people kneel from the Sanctus to the end of the Eucharistic Prayer (GIRM 43).

On Communion the rules are clear. St. Paul warned that "any one who eats and drinks without discerning the body eats and drinks judgment upon himself," and the Catechism concludes: "Anyone conscious of a grave sin must receive the sacrament of Reconciliation before coming to communion" (CCC 1385). Canon law requires a fast of "at least one hour before holy communion from any food and drink, except for only water and medicine" (can. 919). Our posts on mortal sin and on missing Sunday Mass cover the hard cases.

None of this is a test you can fail by sitting in the wrong place. Justin's Christians read, prayed, gave thanks and shared the bread because the Lord had told them to. Nineteen centuries later the Mass still does exactly that, and the simplest way to understand it is to go and let it happen around you.