Adoremus, Society for the Renewal of the Sacred Liturgy
Pope Paul VI
Effective January 1, 1973, Pope Paul VI, by his “motu proprio” Ministeria Quaedam, revised “certain ministries”, or liturgical offices. He eliminated the “minor orders” of porter, lector (reader), exorcist and acolyte, and the subdiaconate; and he established the offices of lector and acolyte as instituted ministries “more closely associated with the Word and the altar” available to approved lay men, as well as to seminarians.
The “motu proprio” was dated August 15, 1972, and was followed by the Rite of Institution of Readers and Acolytes, issued by the Congregation for Divine Worship on December 3, 1972, also becoming effective January 1 (Latin edition). (Formal institution by the bishop as reader is not required, however, for serving as a reader at Mass.)
Apostolic Letter given Motu Proprio:
On first tonsure, minor orders, and the subdiaconate
Certain ministries were established by the Church even in the most ancient times for the purpose of suitably giving worship to God and for offering service to the people of God according to their needs. By these ministries, the offices to be carried out in the liturgy and the practice of charity, deemed suitable to varying circumstances, were entrusted to the faithful. The conferring of these functions often took place by a special rite, in which, after God’s blessing had been implored, a Christian was established in a special class or rank for the fulfillment of some ecclesiastical function.
Some of these functions, which were more closely connected with the liturgical celebration, slowly came to be considered as a training in preparation for the reception of sacred orders. As a result, the offices of porter, reader, exorcist, and acolyte were called minor orders in the Latin Church in relation to the subdiaconate, diaconate, and priesthood, which were called major orders. Generally, though not every where, these minor orders were reserved to those who received them as steps toward the priesthood.
Nevertheless, since the minor orders have not always been the same and many functions connected with them, as at present, have also been exercised by the laity, it seems fitting to reexamine this practice and to adapt it to contemporary needs. What is obsolete in these offices will thus be removed and what is useful retained; also anything new that is needed will be introduced and at the same time the requirements for candidates for holy orders will be established.
While Vatican Council II was in preparation, many bishops of the Church requested that the minor orders and subdiaconate be revised. Although the Council did not decree anything concerning this for the Latin Church, it stated certain principles for resolving the issue. There is no doubt that the norms laid down by the Council regarding the general and orderly reform of the liturgy  also include those areas that concern ministries in the liturgical assembly, so that the very arrangement of the celebration itself makes the Church stand out as being formed in a structure of different orders and ministries.  Thus Vatican Council II decreed that "in liturgical celebrations each one, minister or layperson, who has an office to perform, should do all of, but only, those parts which pertain to that office by the nature of the rite and the principles of liturgy." 
With this assertion is closely connected what was written a little earlier in the same Constitution: "The Church earnestly desires that all the faithful be led to that full, conscious, and active participation in liturgical celebrations called for by the very nature of the liturgy. Such participation by the Christian people as ‘a chosen race, a royal priesthood, a holy nation, a purchased people’ (I Pt 2:9; see 2:4-5) is their right and duty by reason of their baptism. In the reform and promotion of the liturgy, this full and active participation by all the people is the aim to be considered before all else. For it is the primary and indispensable source from which the faithful are to derive the true Christian spirit and therefore pastors must zealously strive in all their pastoral work to achieve such participation by means of the necessary instruction." 
Among the particular offices to be preserved and adapted to contemporary needs are those that are in a special way more closely connected with the ministries of the word and of the altar and that in the Latin Church are called the offices of reader and acolyte and the subdiaconate. It is fitting to preserve and adapt these in such a way, that from this time on there will be two offices: that of reader and that of acolyte, which will include the functions of the subdiaconate.
In addition to the offices universal in the Latin Church, the conferences of bishops may request others of the Apostolic See, if they judge the establishment of such offices in their region to be necessary or very useful because of special reasons. To these belong, for example, the ministries of porter, exorcist, catechist,  as well as others to be conferred on those who are dedicated to works of charity, where this ministry had not been assigned to deacons.
It is in accordance with the reality itself and with the contemporary outlook that the above-mentioned ministries should no longer be called minor orders; their conferral will not be called ordination, but institution. Only those who have received the diaconate, however, will be clerics in the true sense and will be so regarded. This arrangement will bring out more clearly the distinction between clergy and laity, between what is proper and reserved to the clergy and what can be entrusted to the laity. This will also bring out more clearly that mutuality by which "the universal priesthood of believers and the ministerial or hierarchic priesthood, though they differ from one another in essence and not only in degree, are nonetheless interrelated: each of these in its own special way is a sharing in the one priesthood of Christ." 
After weighing every aspect of the question, seeking the opinion of experts, consulting with the conferences of bishops and taking their views into account, and after taking counsel with our esteemed brothers who are members of the congregations competent in this matter, by our apostolic authority we enact the following norms, amending-if and in so far as is necessary-provisions of the Codex Iuris Canonici now in force, and we promulgate them through this Motu Proprio.
1. First tonsure is no longer conferred; entrance into the clerical state is joined to the diaconate.
2. What up to now were called minor orders are henceforth to be called ministries.
3. Ministries may be assigned to lay Christians; hence they are no longer to be considered as reserved to candidates for the sacrament of orders.
4. Two ministries, adapted to present-day needs, are to be preserved in the whole Latin Church, namely, those of reader and acolyte. The functions heretofore assigned to the subdeacon are entrusted to the reader and the acolyte; consequently, the major order of subdiaconate no longer exists in the Latin Church. There is, however, no reason why the acolyte cannot be called a subdeacon in some places, at the discretion of the conference of bishops.
5. The reader is appointed for a function proper to him, that of reading the Word of God in the liturgical assembly. Accordingly, he is to proclaim the readings from sacred Scripture, except for the gospel in the Mass and other sacred celebrations; he is to recite the psalm between the readings when there is no psalmist; he is to present the intentions for the general intercessions in the absence of a deacon or cantor; he is to direct the singing and the participation by the faithful; he is to instruct the faithful for the worthy reception of the sacraments. He may also, insofar as may be necessary, take care of preparing other faithful who are appointed on a temporary basis to read the Scriptures in liturgical celebrations. That he may more fittingly and perfectly fulfill these functions, he is to meditate assiduously on sacred Scripture.
Aware of the office he has undertaken, the reader is to make every effort and employ suitable means to acquire that increasingly warm and living love  and knowledge of Scripture that will make him a more perfect disciple of the Lord.
6. The acolyte is appointed in order to aid the deacon and to minister to the priest. It is his duty therefore to attend to the service of the altar and to assist the deacon and the priest in liturgical celebrations, especially in the celebration of Mass; he is also to distribute communion as a special minister when the ministers spoken of in the Codex Iuris Canonici can. 845 are not available or are prevented by ill health, age, or another pastoral ministry from performing this function, or when the number of communicants is so great that the celebration of Mass would be unduly prolonged. In the same extraordinary circumstances an acolyte may be entrusted with publicly exposing the blessed sacrament for adoration by the faithful and afterward replacing it, but not with blessing the people. He may also, to the extent needed, take care of instructing other faithful who on a temporary basis are appointed to assist the priest or deacon in liturgical celebrations by carrying the missal, cross, candles, etc., or by performing other such duties. He will perform these functions more worthily if he participates in the Holy Eucharist with increasingly fervent devotion, receives nourishment from it, and deepens his knowledge about it.
As one set aside in a special way for the service of the altar, the acolyte should learn all matters concerning public divine worship and strive to grasp their inner spiritual meaning: in that way he will be able each day to offer himself entirely to God, be an example to all by his gravity and reverence in church, and have a sincere love for the Mystical Body of Christ, the people of God, especially for the weak and the sick.
7. In accordance with the ancient tradition of the Church, institution to the ministries of reader and acolyte is reserved to men.
8. The following are requirements for admission to the ministries:
1. the presentation of a petition that has been freely made out and signed by the aspirant to the Ordinary (the bishop and, in clerical institutes, the major superior) who has the right to accept the petition;
2. a suitable age and special qualities to be determined by the conference of bishops;
3. a firm will to give faithful service to God and the Christian people.
9. The ministries are conferred by the Ordinary (the bishop and, in clerical institutes, the major superior) through the liturgical rite De institutione lectoris and De institutione acolythi as revised by the Apostolic See.
10. An interval, determined by the Holy See or the conferences of bishops, shall be observed between the conferring of the ministries of reader and acolyte whenever more than one ministry is conferred on the same person.
11. Unless they have already done so, candidates for ordination as deacons and priests are to receive the ministries of reader and acolyte and are to exercise them for a suitable time, in order to be better disposed for the future service of the word and of the altar. Dispensation from receiving these ministries on the part of such candidates is reserved to the Holy See.
12. The conferring of ministries does not bring with it the right to support or remuneration from the Church.
13. The rite of institution of readers and acolytes will soon be published by the competent department of the Roman Curia.
The effective date of these norms is January 1, 1973.
We command as established and confirmed whatever this Motu Proprio has decreed, all things to the contrary notwithstanding.
Given in Rome, at Saint Peter’s, on August 15, 1972, the Solemnity of the Assumption, the tenth year of our pontification.
1. See Sacrosanctum Concilium art. 62; see also art. 21
2. See GIRM no. 58
3. Sacrosanctum Concilium art. 28
4. Sacrosanctum Concilium art. 14
5. See AG no. 15: AAS 58 (1966) 965; ConsDecrDecl 574; see also AG no. 17 [DOL 17 no. 249]
6. Lumen Gentium no. 10
7. See Sacrosanctum Concilium art. 24; Dei Verbum no. 25