In some Christian denominations, a reader or lector is the person responsible for reading aloud excerpts of scripture at a liturgy. In early Christian times the reader was of particular value due to the rarity of literacy.

In the Latin liturgical rites of the Catholic Church, the term lector or reader means someone who in a particular liturgy is assigned to read a Biblical text other than the Gospel (singing or reading the Gospel at Mass belongs to the service of the deacon or, in his absence, to the priest). But it also has the more specific meaning of a person who has been "instituted" as a lector or reader, and is such even when not assigned to read in a specific liturgy. The Second Vatican Council's Sacrosanctum Concilium, the Second Vatican Council's Constitution on the Sacred Liturgy, confirmed that lectors belong to those who exercise a "genuine liturgical function" and should therefore "discharge their office with the sincere piety and decorum demanded by so exalted a ministry and rightly expected of them by God's people."

The office was formerly classed as one of the four minor orders in the Latin Church. However, since 1 January 1973, the apostolic letter Ministeria quaedam decreed instead that:

Canon 1035 of the 1983 Code of Canon Law requires candidates for diaconal ordination to have received and have exercised for an appropriate time the ministries of lector and acolyte and prescribes that institution in the second of these ministries must precede by at least six months ordination as a deacon.

Instituted lectors, either men or women (since the 2021 motu proprio Spiritus Domini), are obliged, when proclaiming the readings at Mass, to wear an alb or an "other suitable attire that has been legitimately approved by the Conference of Bishops". such as cassock and surplice. Others who perform the function of lector, "may go to the ambo in ordinary attire, but this should be in keeping with the customs of the different regions."

The General Instruction of the Roman Missal speaks as follows of those who, without being lectors in the specific sense, carry out their functions at Mass: "In the absence of an instituted lector, other lay people may be deputed to proclaim the readings from Sacred Scripture, people who are truly suited to carrying out this function and carefully prepared, so that by their hearing the readings from the sacred texts the faithful may conceive in their hearts a sweet and living affection for Sacred Scripture." In its sections the same document lists the lector's specific duties at Mass.

Traditionalist Catholic organizations such as the Priestly Fraternity of St. Peter, the Institute of Christ the King Sovereign Priest and the Personal Apostolic Administration of Saint John Mary Vianney are authorized to use the pre-1973 rite for their members who receive the office of lector.

In the Eastern Orthodox Church and in the Eastern Catholic Churches of Byzantine tradition, the reader (in Greek, Ἀναγνώστης Anagnostis; in Church Slavonic, чтец chtets) is the second highest of the minor orders of clergy. This order is higher than the doorkeeper (now largely obsolete) and lower than the subdeacon.