The celebration of Mass is a corporate act, an act of the whole assembly gathered for worship. All the particular ministries serve this corporate function (GIRM, no. 27). In the Mass, the Church is joined to the action of Christ, the high point both of the action by which God sanctifies the world in Christ and of the worship that the human race offers to the Father, adoring him through Christ, the Son of God, in the Holy Spirit (no. 16). We are joined to this divine action through baptism, which incorporates us into the risen Christ. This action, which lies at the center of the whole Christian life (no. 16) is not initiated by us but by God acting in and through the Church as the body of the risen Christ.

It becomes our action only to the extent that we give ourselves to this mystery of redemptive worship. The liturgy is designed to bring about in all those who make up the worshiping assembly a participation of the faithful both in body and mind, a participation burning with faithful, hope, and charity (no. 18). To the extent that we are able to participate in this way, the work of redemption becomes personally effective for each of us. By such participation, the General Instruction says, we make the actions and prayers of the liturgy our own; we enter more fully into our personal communion with Christ's redeeming act and perfect worship (see no. 54, 55, etc.).

In the celebration of Mass the faithful are a holy people, a chosen people, a royal priesthood: they give thanks to God and offer the Victim not only through the hands of the priest but also together with him and learn to offer themselves. They should endeavor to make this clear by their deep sense of reverence for God and their charity toward brothers and sisters who share with them in the celebration (no. 95). They should become one body, whether by hearing the word of God, or joining in prayers and liturgical song, or above all by offering the sacrifice together and sharing together in the Lord's table (no. 96).

Because the whole liturgy is a corporate act of the gathered assembly (GIRM no. 34; Catechism of the Catholic Church no. 1144), there are certain parts of the Mass that are to be done by the whole assembly, the congregation of the faithful and all the ministers, in order to express the corporate nature of this act. Through these actions, the entire congregation of the faithful joins itself to Christ in acknowledging the great things that God has done and in offering the sacrifice (no. 78). These acts include:

• Listening with reverence to the readings of God's word (GIRM no. 29);
  
• Engaging in the dialogue of prayer through acclamations, greetings, and responses to spoken and sung prayers (no. 34-37) in a tone suitable to the text (no. 38);
  
• Joining in an action through common postures and gestures (no. 42);
  
• Participating in communal silence (no. 45);
  
• Because of their baptismal dignity, letting themselves be included in the offering symbolized by incensation (no. 75);
  
• Participating in the greeting of peace as a sign of ecclesial communion and love for each other (no. 82);
  
• Participating in specific spoken prayers and other texts, namely:
  
• the formula of general confession during the penitential rite (no. 51);
  
• the profession of faith (no. 67-68);
  
• the general intercessions (no. 69);
  
• the Lord's Prayer (no. 81);
  
• the prayer of humility before sacramental communion (no. 84);
  
• Participating in the offering during the Eucharistic Prayer, which is spoken or chanted by the priest, but in which all should join as the Church to offer the "spotless Victim to the Father in the Holy Spirit" and "offer themselves and so day by day to surrender themselves, through Christ the Mediator, to an ever more complete union with God and with each other, so that at last God may be all in all" (no. 79f);
  
• Participating in liturgical song, because singing is a way of expressing both the corporate nature of the act of worship and the intense union to be achieved between God and the Church in Christ through the Holy Spirit. It is a union so intense and total that it is described as a union between lovers whose nature is best expressed vocally in song (no. 39). Singing is also an act which unifies and focuses the individual (no. 39), thus encouraging that "participation in body and spirit that is conscious, active, full, and motivated by faith, hope, and charity" (no. 18). These songs and acclamations are normally to be sung, in whole or in part, by all the participants:
  
• opening liturgical song (no. 48);
  
• Kyrie (no. 52);
  
• Gloria (no. 53);
  
• Responsorial psalm (no. 61);
  
• Gospel acclamation (no. 62);
  
• Song at the preparation of gifts (no. 74);
  
• Sanctus, memorial acclamation, and Amen (no. 79, 151);
  
• The Lord's Prayer (no. 81);
  
• Lamb of God (no. 83);
  
• the optional psalm, canticle of praise, or hymn after communion (no. 88).
  
• For those who are properly disposed (no. 80), full, active, and conscious participation is expressed in partaking in the Holy Communion of the Lord, receiving in the one bread consecrated at this Mass the Lord's body and blood, in the same way that the apostles received them from Christ's own hands (no. 72.3).