Chapter I-IV. Participants in the Liturgy of the Hours
Celebration In Common
20. The liturgy of the hours, like other liturgical services, is not a private matter
but belongs to the whole Body of the Church, whose life it both expresses and
affects.  This liturgy stands out most strikingly as an ecclesial celebration when,
through the bishop surrounded by his priests and ministers,  the local Church
celebrates it. For "in the local Church the one, holy, catholic, and apostolic Church
is truly present and at work."  Such a celebration is therefore most earnestly
recommended. When, in the absence of the bishop, a chapter of canons or other
priests celebrate the liturgy of the hours, they should always respect the true time
of day and, as far as possible, the people should take part. The same is to be said of collegiate chapters.
21. Wherever possible, other groups of the faithful should celebrate the liturgy of the hours communally in church. This especially applies to parishes - the cells of the diocese, established under their pastors, taking the place of the bishop; they "represent in some degree the visible Church established throughout the world." 
22. Hence, when the people are invited to the liturgy of the hours and come together in unity of heart and voice, they show forth the Church in its celebration of the mystery of Christ. 
23. Those in holy orders or with a special canonical mission  have the responsibility of initiating and directing the prayer of the community; "they should expend every effort so that those entrusted to their care may become of one mind in prayer."  They must therefore see to it that the people are invited, and prepared by suitable instruction, to celebrate the principal hours in common, especially on Sundays and holydays.  They should teach the people how to make this participation a source of genuine prayer;  they should therefore give the people suitable guidance in the Christian understanding of the psalms, in order to progress by degrees to a greater appreciation and more frequent use of the prayer of the Church. 
24. Communities of canons, monks, nuns, and other religious who celebrate the liturgy of the hours by rule or according to their constitutions, whether with the general rite or a particular rite, in whole or in part, represent in a special way the Church at prayer. They are a fuller sign of the Church as it continuously praises God with one voice and they fulfill the duty of "working," above all by prayer, "to build up and increase the whole Mystical Body of Christ, and for the good of the local Churches."  This is especially true of those living the contemplative life.
25. Even when having no obligation to communal celebration, all sacred ministers and all clerics living in a community or meeting together should arrange to say at least some part of the liturgy of the hours in common, particularly morning prayer and evening prayer. 
26. Men and women religious not bound to a common celebration, as well as members of any institute of perfection, are strongly urged to gather together, by themselves or with the people, to celebrate the liturgy of the hours or part of it.
27. Lay groups gathering for prayer, apostolic work, or any other reason are encouraged to fulfill the Church's duty,  by celebrating part of the liturgy of the hours. The laity must learn above all how in the liturgy they are adoring God the Father in spirit and in truth;  they should bear in mind that through public worship and prayer they reach all humanity and can contribute significantly to the salvation of the whole world. 
Finally, it is of great advantage for the family, the domestic sanctuary of the Church, not only to pray together to God but also to celebrate some parts of the liturgy of the hours as occasion offers, in order to enter more deeply into the life of the Church. 
Mandate to Celebrate the Liturgy of the Hours
28. Sacred ministers have the liturgy of the hours entrusted to them in such a particular way that even when the faithful are not present they are to pray it themselves with the adaptations necessary under these circumstances. The Church commissions them to celebrate the liturgy of the hours so as to ensure at least in their persons the regular carrying out of the duty of the whole community and the unceasing continuance of Christ's prayer in the Church. 
The bishop represents Christ in an eminent and conspicuous way and is the high priest of his flock; the life in Christ of his faithful people may be said in a sense to derive from him and depend on him.  He should, then, be the first of all the members of his Church in offering prayer. His prayer in the recitation of the liturgy of the hours is always made in the name of the Church and on behalf of the Church entrusted to him. 
United as they are with the bishop and the whole presbyterium, priests are themselves representative in a special way of Christ the Priest  and so share the same responsibility of praying to God for the people entrusted to them and indeed for the whole world. 
All these ministers fulfill the ministry of the Good Shepherd who prays for his
sheep that they may have life and so be brought into perfect unity.  In the liturgy of the hours that the Church sets before them they are not only to find a source of devotion and a strengthening of personal prayer,  but must also nourish and foster pastoral missionary activity as the fruit of their contemplation to gladden the whole Church of God. 
29. Hence bishops, priests, and other sacred ministers, who have received from the Church the mandate to celebrate the liturgy of the hours (see no. 17), should recite
the full sequence of hours each day, observing as far as possible the true time of day.
They should, first and foremost, attach due importance to those hours that are, so to speak, the two hinges of the liturgy of the hours, that is, morning prayer and evening prayer, which should not be omitted except for a serious reason.
They should faithfully pray the office of readings, which is above all a liturgical celebration of the word of God. In this way they fulfill daily a duty that is peculiarly their own, that is, of receiving the word of God into their lives, so that they may become more perfect as disciples of the Lord and experience more deeply the unfathomable riches of Christ. 
In order to sanctify the whole day more completely, they will also treasure the recitation of daytime prayer and night prayer, to round off the whole Opus Dei and to commend themselves to God before retiring.
30. It is most fitting that permanent deacons recite daily at least some part of the liturgy of the hours, to be determined by the conference of bishops. 
31. a. Cathedral and collegiate chapters should celebrate in choir those parts of the liturgy of the hours that are prescribed for them by the general law or by particular law.
In private recitation individual members of these chapters should include those hours that are recited in their chapter, in addition to the hours prescribed for all sacred ministers. 
b. Religious communities bound to the recitation of the liturgy of the hours and their individual members should celebrate the hours in keeping with their own particular law; but the prescription of no. 29 in regard to those in holy orders is to be respected.
Communities bound to choir should celebrate the whole sequence of the hours daily in choir;  when absent from choir their members should recite the hours in keeping with their own particular law; but the prescriptions in no. 29 are always to be respected.
32. Other religious communities and their individual members are advised to celebrate some parts of the liturgy of the hours, in accordance with their own situation, for it is the prayer of the Church and makes the whole Church, scattered throughout the world, one in heart and mind.  This recommendation applies also to laypersons. 
Structure of the Celebration
33. The structure of the liturgy of the hours follows laws of its own and incorporates in its own way elements found in other Christian celebrations. Thus it is so constructed that, after a hymn, there is always psalmody, then a long or short reading of sacred Scripture, and finally prayer of petition.
In a celebration in common and in private recitation the essential structure of this liturgy remains the same, that is, it is a conversation between God and his people. Celebration in common, however, expresses more clearly the ecclesial nature of the liturgy of the hours; it makes for active participation by all, in a way suited to each one's condition, through the acclamations, dialogue, alternating psalmody, and similar elements. It also better provides for the different literary genres that make up the liturgy of the hours.  Hence, whenever it is possible to have a celebration in common, with the people present and actively taking part, this kind of celebration is to be preferred to one that is individual and, as it were, private.  It is also advantageous to sing the office in choir and in community as opportunity Offers, in accordance with the nature and function of the individual parts.
In this way the Apostle's exhortation is obeyed: "Let the word of Christ dwell in you in all its fullness, as you teach and counsel each other in all wisdom by psalms, hymns, and spiritual canticles, singing thankfully to God in your hearts" (Col 3:16; see Eph 5:19-20).