In Christian cultures, the term lay priest is sometimes used in the past to refer to a secular priest, a diocesan priest who is not a member of a religious institute. Terms such as lay priest, lay clergy and lay nun were also once used in Buddhist cultures to indicate ordained persons who continued to live in the wider community instead of retiring to a monastery.
In the context of specialized professions, the term lay is often used to refer to those who are not members of that profession.
Christian laity 
In Anglicanism, the term "laity" refers to anyone who is not a bishop, priest, or deacon in the Church. In the Anglican tradition, all baptized persons are expected to minister in Christ's name. The orders of ministry are thus laymen, deacons, priests, and bishops.
The ministry of the laity is "to represent Christ and his Church; to bear witness to him wherever they may be; and, according to the gifts given them, to carry on Christ's work of reconciliation in the world; and to take their place in the life, worship, and governance of the Church". Much of the ministry of the laity thus takes place outside official church structures in homes, workplaces, schools, and so forth. Laymen also play important roles in the structures of the church.
There are elected lay representatives on the various governing bodies of churches in the Anglican communion. In the Church of England, these governing bodies range from a local Parochial Church Council, through Deanery Synods and Diocesan Synods. At the topmost level, the General Synod includes a house of Laity. Likewise, in the Episcopal Church in the USA the General Convention includes four laymen from each diocese in the House of Deputies, and each diocesan convention includes lay delegates from the parishes. On the local parish level, laymen are elected to a church council called a vestry which manages church finances and elects the parish rector.
Parish musicians, bookkeepers, administrative assistants, sextons, sacristans, etc., are all roles normally filled by laymen. At higher levels, diocesan and national offices rely on laymen in many important areas of responsibility. Often specialized ministries as campus ministers, youth ministers, or hospital chaplains are performed by laymen.
Laymen serve in worship services in a number of important positions, including vergers, acolytes, lectors, intercessors, ushers, and so forth. Acolytes include torch bearers, crucifers, thurifers, and boat bearers. Lectors read the lessons from the Bible appointed for the day (except for the Gospel reading, which is read by a Deacon), and may also lead the Prayers of the People.
Some specialized lay ministries require special licensing by the bishop. Which ministries require a license varies from province to province. In the Episcopal Church, there are six specialized lay ministries requiring a license: Pastoral Leader, Worship Leader, Preacher, Eucharistic Minister, Eucharistic Visitor, and Catechist.
Roman Catholicism 
The Second Vatican Council [1962–1965] devoted its decree on the apostolate of the laity Apostolicam actuositatem and chapter IV of its dogmatic constitution Lumen gentium to the laity in a sense narrower than that which is normal in the Catholic Church. The normal definition of laity is that given in the Code of Canon Law:
|“||By divine institution, there are among the Christian faithful in the Church sacred ministers who in law are also called clerics; the other members of the Christian faithful are called lay persons.
There are members of the Christian faithful from both these groups who, through the profession of the evangelical counsels by means of vows or other sacred bonds recognized and sanctioned by the Church, are consecrated to God in their own special way and contribute to the salvific mission of the Church; although their state does not belong to the hierarchical structure of the Church, it nevertheless belongs to its life and holiness.
The narrower sense in which the Second Vatican Council gave instruction concerning the laity is as follows:
|“||The term laity is here understood to mean all the faithful except those in holy orders and those in the state of religious life specially approved by the Church. These faithful are by baptism made one body with Christ and are constituted among the People of God; they are in their own way made sharers in the priestly, prophetical, and kingly functions of Christ; and they carry out for their own part the mission of the whole Christian people in the Church and in the world.||”|
In this narrower sense, the Council taught that the laity's specific character is secularity: they are Christians who live the life of Christ in the world. Their role is to sanctify the created world by directing it to become more Christian in its structures and systems: "the laity, by their very vocation, seek the kingdom of God by engaging in temporal affairs and by ordering them according to the plan of God". The laity are full members of the Church, fully share in Church's purpose of sanctification, of "inner union of men with God", acting with freedom and personal responsibility and not as mere agents of the hierarchy. Due to their baptism, they are members of God's family, the Church, and they grow in intimate union with God, "in" and "by means" of the world. It is not a matter of departing from the world as the monks and the nuns do that they sanctify themselves; it is precisely through the material world sanctified by the coming of the God made flesh, i.e. made material, that they reach God. Doctors, mothers of a family, farmers, bank tellers, drivers, by doing their jobs in the world with a Christian spirit are already extending the Kingdom of God. According to the repeated statements of Popes and lay Catholic leaders, the laity should say "we are the Church," in the same way that the saints said that "Christ lives in me."
Lay involvement takes diverse forms, including participation in the life of the parish, confraternities, lay apostolates, secular institutes, and lay ecclesial movements. There are also lay ecclesiastical ministries, and where there is a priest shortage, lay people have to take on some functions previously performed by priests.
Methodist lay preacher 
A very early tradition of preaching in the Wesleyan / Methodist churches was for a lay preacher to be appointed to lead services of worship and preach in a group (called a 'circuit') of meeting places or churches. The lay preacher walked or rode on horseback in a prescribed circuit of the preaching places according to an agreed pattern and timing, and people came to the meetings. After the appointment of ministers and pastors, this lay preaching tradition continued with local preachers being appointed by individual churches, and in turn approved and invited by nearby churches, as an adjunct to the minister or during their planned absences.
In addition to being appointed by members of their local churches, Local and Certified Lay Speakers of the United Methodist Church (more commonly in the United States) attend a series of training sessions. These training sessions prepare the individual to become a leader within the church. All individuals who are full members of the church are laity, but some go on to become Lay Speakers. Some preachers get their start as Lay Speakers.
- by the congregation as a Lay Preacher; and/or
- by the regional Presbytery to conduct Communion.
The comparable term in the Anglican and Episcopal churches is Lay Reader.
Presbyterians do not use the term "lay". Thus the Church of Scotland has "Readers", men and women set apart by presbyteries to conduct public worship. This arises out of the belief in the priesthood of all believers. Ministers are officially 'teaching elders' alongside the 'ruling elders' of the Kirk Session and have equivalent status, regardless of any other office. In the Church of Scotland, as the Established church in Scotland, this gives ruling elders in congregations the same status as Queen's chaplains, professors of theology and other highly qualified ministers. All are humble servants of the people in the congregation and parish. Ministers are simply men and women whose gift is for their role in teaching and possibly pastoral work. They are thus selected for advanced theological education. All elders (teaching and ruling) in meetings of Session, Presbytery, or Assembly are subject to the Moderator, who may or may not be a minister but is always an elder.
The Church of Jesus Christ of Latter-day Saints 
The Church of Jesus Christ of Latter-day Saints practices the principle of having a lay ministry. Essentially all worthy male members above the age of 12 are ordained to an office of the priesthood and hold various positions in the church. With the exception of General Authorities, all leadership positions are temporary. Permanent positions are only held by apostles and the First Quorum of the Seventy. They are also unpaid positions, and they are often called to these positions after a long secular career.
Buddhist lay persons 
In Buddhism, a layperson is known as an upasaka (masc.) or upasika (fem.). Buddhist laypeople take refuge in the Triple Gem (the Buddha, his teaching, and his community of noble disciples) and accept the Five Precepts (or the Eight Precepts) as rules for conduct. Laymen and laywomen are two of the "four assemblies" that comprise the Buddha's "Community of Disciples."
In Chinese Buddhism, there are usually laypersons, who are depicted wearing a black robe and sometimes a brown sash, denoting that they received the five precepts.
- Laity at the Catholic Encyclopedia
- Book of Common Prayer of the Episcopal Church in the United States of America p. 855
- Canon 4, Title III, Constitution & Canons Together with the Rules of Order for the Government of the Protestant Episcopal Church in the United States of America, Adopted and Revised in General Convention, 2006
- Apostolicam actuositatem
- Code of Canon Law, canon 207
- Lumen gentium, 31
- Catechism of the Catholic Church, 775
-  The Code of Canon Law (Roman Catholic Church)
-  The Religions of South Vietnam in Faith and Fact: V. Buddhism in Vietnam (Section E. DEFINITIONS AND EXPLANATION OF BUDDHIST TERMS)