In the Catholic Church the term minister enjoys a variety of usages. It most commonly refers to the person, whether lay or ordained, who is commissioned to perform some act on behalf of the Church. It is not a particular office or rank of clergy, as is the case in some other churches, but minister may be used as a collective term for vocational or professional pastoral leaders including clergy (bishops, deacons, priests) and non-clergy (theologians and lay ecclesial ministers). It is also used in reference to the canonical and liturgical administration of sacraments, as part of some offices, and with reference to the exercise of the lay apostolate.
Minister is not used as a form of address (e.g., Minister Jones) in the Catholic Church.
Scripturally, various passages utilize the language of servant (ministri) to indicate those charged with spiritual functions or pastoral care of the community: 1 Corinthians 4:1–2; Hebrews 8:2; Matthew 20:26, etc.
Specific distinction in terminology may be found in various documents, among others: Participation of the Lay Faithful in the Presbyteral Ministry.
The Church calls people to the responsible stewardship of their time and talent in support of the Church. This often takes the form of volunteering for a specific lay ministry, most of which are liturgical, catechetical, or involved in pastoral care and social justice.
Liturgical lay ministries include lectors (Ministers of the Word) who proclaim scriptural (the Bible) passages during the Eucharist, altar servers and acolytes who assist the presider at the altar, cantors and music ministers who lead the singing, extraordinary ministers of Holy Communion who serve during Mass and/or who take Holy Communion to the sick and homebound, and ushers or ministers of hospitality who direct the seating and procession of the assembly.
Catechetical lay ministries include catechists (Sunday school teachers and teachers at Catholic schools), dismissal leaders (ministers who lead RCIA catechumens on Sundays), retreat leaders, youth group leaders, and Scout religious emblems counselors.
Other lay ministries include those who work with charitable activities, pastoral care and outreach, or advocacy for social justice.
Some persons within the church are called by God and the assembly to serve as ministers to the whole people of God. These people respond to this vocation by receiving the proper formation, usually including graduate studies in theology or divinity, and then exercising some leadership role in the community. In common usage, when someone refers to a "minister of the church" they are referring to any one of these "professional" ministers.
The Catholic Church identifies five ecclesial vocations, three of which are ordained. Theologians and lay ecclesial ministers are not necessarily ordained, while bishops, presbyters, and deacons are ordained. While only the latter are considered clergy by the Catholic Church, all are considered ministers in the professional and vocational sense.
The other kind of minister in Catholic parlance is a person who administers a sacrament, meaning that he or she is a conduit of sacramental grace. This is not an office or position but instead a function that different kinds of people may perform, depending on the sacrament. There are two kinds of ministers in this sense. The ordinary minister of a sacrament, who is the standard or normal minister of that sacrament, has the spiritual power to administer it (i.e., a valid sacrament), but not necessarily the canonical authority to administer it (i.e., a licit sacrament). Thus a bishop who consecrates another bishop without pontifical mandate exercises illicitly the spiritual power to consecrate him. While bishops, priests and deacons are ordinary ministers of holy communion, only someone who has been validly ordained as a priest is a minister of the Eucharist. If a priest is, for some reason, debarred  and yet celebrates the Eucharist, he does so illicitly (i.e. against canon law), but the Eucharist is still valid. However, in the case of the sacrament of Reconciliation (the Sacrament of Penance), although the priest is the minister, the only minister, since there are no extraordinary ministers of this sacrament, he must have been granted by the law itself or by a competent authority the faculty to celebrate this sacrament validly for the person to whom he imparts absolution.
An extraordinary minister (Latin: minister extraordinarius) of a sacrament is someone, other than an ordinary minister, officially authorised to administer a sacrament by the law itself (as an instituted acolyte is an extraordinary minister of holy communion) or by being deputed for this purpose. If an extraordinary minister of a sacrament administers it illicitly, the sacrament is effective, but the person ministering could be liable for an ecclesiastical penalty, such as an interdict. By way of example, an extraordinary minister of Holy Communion is authorised to bring Holy Communion within a particular parish or diocese. If a minister brings Holy Communion to someone outside of the authorised area, it is done illicitly, but the communicant does receive Holy Communion, as indeed the communicant would, even if the person administering it had no authorisation whatever.
If a person who is not an ordinary minister of certain sacraments attempts to celebrate them, the sacraments are invalid.
Below is a table outlining each sacrament, its ordinary ministers, and its extraordinary ministers (if any), with stipulations regarding its exercise by extraordinary ministers in parenthesis.
|Sacrament||Ordinary ministers||Extraordinary ministers|
|Baptism||any clergy1||in the absence of clergy, a catechist or other person designated by the local ordinary|
in emergencies, any person with the right intention, even if not baptised (in other circumstances illicit but valid)
|Confirmation||bishop||priests who are equivalent in law to a diocesan bishop for their subjects, or who legitimately baptise or receive into the Church an adult, or who are acting in danger of death for the person being confirmed or who have been specifically granted the faculty by the diocesan bishop (invalid if administered by other priests or by persons who are not priests)|
|Eucharist (consecration)²||bishop or priest||none; always invalid if attempted by others|
|Distribution of Holy Communion³||clergy (including deacons)||instituted acolyte (licit when not enough or no clergy are available)|
other laity deputed for the purpose (licit when not enough or no clergy or instituted acolytes available)
|Reconciliation||bishop or priest||none; invalid if done by a layperson or by a priest without faculties (which the law provides for any priest absolving someone who is in danger of death)|
|Anointing of the Sick||bishop or priest||none; invalid if done by anyone else|
|Holy Orders (bishop)4||bishop ||none; licit only by papal mandate and, if there are no co-consecrators, by papal dispensation, but still valid without these authorisations|
|Holy Orders (priest and deacon)||bishop||none; licit only if the bishop is ordaining his own subjects who are of the same rite or those who have been given dimissorial letters, and only if the bishop is ordaining in his own territory or with the permission of the local bishop|
|Holy Matrimony||husband and wife||none; invalid if contracted other than before the local ordinary or parish priest or a priest or deacon delegated by them and before two witnesses (some exceptions to this condition are envisaged in canon law)|
In certain traditionalist Catholic priestly societies, whether enjoying the favour of the Holy See (like the Priestly Fraternity of St. Peter) or not (like the Society of St. Pius X), the rites of conferring of tonsure, what were called minor orders (of Porter, Lector, Exorcist, and Acolyte) and subdiaconate continue to be used, as before the coming into force of the apostolic letter Ministeria quaedam of 15 August 1972, which, of the minor orders, which it called instituted ministries, preserved for seminarians being prepared for priesthood those of lector and acolyte, and indicating that episcopal conferences, if they wished, could use the term "subdeacon" instead of "acolyte". The specific functions of all of these, whatever the rite by which they are conferred, are clearly not reserved to them. Lay people may and do perform the functions of a lector or acolyte. Laypersons of good character may act as ushers, porters, lectors, extraordinary ministers of Holy Communion, cantors, or may teach the faith as catechists and may advise the clergy or church courts, including serving as judges on marriage tribunals.
Since the entry into force of the 1983 Code of Canon Law, one becomes a member of the clergy upon ordination to the diaconate. Earlier, it was the rite of tonsure that made one a cleric.