official act mainly of the Roman Catholic Church declaring one of its deceased members worthy of public cult and entering his or her name in the canon, or authorized list, of recognized saints. In the early church there was no formal canonization, but the cult of local martyrs was widespread and was regulated by the bishop of the diocese. The translation of the martyr's remains from the place of burial to a church was equivalent to canonization. Gradually, ecclesiastical authorities intervened more directly in the process of canonization. By the 10th century appeals were made to the pope. The first saint canonized by a pope was Ulrich, bishop of Augsburg, who died in 973 and was canonized by Pope John XV at the Lateran Council of 993. Pope Alexander III (1159–81) began to reserve the cases of canonization to the Holy See, and this became general law under Gregory IX (1227–41).

Pope Sixtus V (1585–90) assigned to the Congregation of Rites, one of the offices of the Roman Curia, the duty of conducting the processes of beatification (i.e., a first step toward canonization, whereby limited public veneration is permitted) and canonization. In the following century Pope Urban VIII forbade the public cult of any person not as yet beatified or canonized by the church. Exception was made only for those who were in possession of public cult from time immemorial or for at least 100 years.

The legislation of Pope Urban VIII, together with later legislation by Pope Benedict XIV, formed the basis of the procedures for beatification and canonization found in the Code of Canon Law (promulgated 1917) of the Roman Catholic Church (Roman Catholicism). Two types of beatification and canonization are distinguished by the Code: formal, or ordinary, and extraordinary, or equivalent.

Formal beatification has entailed four general steps: an informative process, introduction of the cause, the apostolic process, and four definite judgments. The first of these steps was under the jurisdiction of the bishop in whose diocese it took place, the other three were directly under the jurisdiction of the Congregation of Rites and the pope. In the late 1960s Pope Paul VI announced that the process of beatification and canonization would be shortened and decentralized, and he established a new congregation (administrative division) of the Curia to handle such processes. Diocesan, provincial, or regional courts would conduct the entire investigation in consultation with the Vatican. Thus, duplication would be avoided and less time needed to complete the process.

The investigation of the candidate involves the gathering together of all material pertaining to the candidate's reputation for sanctity or heroic virtue, the writings of the candidate, and information about miracles performed by the candidate either during his or her life or after death. The bishop appoints a person, called postulator of the cause, to promote the cause and also a promoter of the faith, commonly known as the “devil's advocate,” to see that the entire truth is made known about the candidate. After the process is completed, if the pope orders the beatification, it is in the form of a solemn proclamation with a solemn mass. Veneration then may be carried on in specified localities.

The canonization process is essentially the same, but at least two authentic miracles obtained through invocation after beatification must occur before the cause for canonization may be introduced. Extraordinary, or equivalent, canonization is simply a papal confirmation that a person is a saint. It is applied only to persons whose veneration was immemorial at the time of Pope Urban VIII (1634).

Canonization in the Eastern Orthodox church (Eastern Orthodoxy) is a solemn proclamation rather than a process. Spontaneous devotion toward an individual by the faithful establishes the usual basis for sainthood. The bishop accepts the petition, examines it, and delivers it to a commission that will render a final decision.

In the Anglican (Anglicanism) church, a commission was appointed in 1950 that discussed in subsequent years (especially at the 1958 Lambeth Conference) the question of canonization for members of its own communion.