Roman Catholic lay and clerical organization whose members seek personal Christian perfection and strive to implement Christian ideals and values in their occupations and in society as a whole. Theologically conservative, Opus Dei accepts the teaching authority of the church without question and has long been the subject of controversy; it has been accused of secrecy, cultlike practices, and political ambitions. With separate branches for men and women, the organization has been headed since 1982 by a prelate elected by its members. Priests constitute only a tiny percentage of the organization, numbering some 1,900 of the 85,000 members worldwide.

Founded in 1928 in Spain by Josemaría Escrivá de Balaguer y Albás (Escrivá de Balaguer, Josemaría, Saint) (canonized in 2002), a priest trained in journalism and law, Opus Dei was formally approved by the Holy See in 1950 as a secular institute (i.e., a new form of religious association whose members “profess the evangelical counsels in secular life”). On Nov. 28, 1982, Pope John Paul II, a staunch supporter of Opus Dei, established it as the first and only personal prelature in the church, with jurisdiction over people rather than a geographic area. The prelate can establish seminaries and promote students to holy orders, but the organization remains subject to some oversight by local bishops.

Some members of Opus Dei, called numeraries, devote much of their time to the organization. Like priests, they are required to remain unmarried and to take vows of celibacy, obedience, and chastity, but they live in the world and pursue secular occupations. They commonly practice self-sacrifice and self-mortification, which can include fasting, abstinence from certain pleasures, and the wearing of a cilice (which often takes the form of a spiked chain worn around the upper thigh). The majority of members, however, are the supernumeraries, who are free to marry, contribute financially to Opus Dei, and demonstrate Christian virtue in their daily activities. Members serve a period of probation and attend monthly meetings and a religious retreat. The group is assisted by cooperators, who are not members and, by permission of the Holy See, need not even be Christians.

Because Opus Dei included many highly educated people, Spain's leader Generalissimo Francisco Franco (Franco, Francisco) involved several of its members in instituting economic reform in 1956, and among his ministers were members of Opus Dei. After Franco's death in 1975, Opus Dei's influence waned in Spain as other groups entered the political arena.

Aggressive recruiting practices, the brainwashing of new recruits, and the isolation of members from their families are among the charges often leveled against the organization. Pointing to its continued growth, Opus Dei denies these accusations.

The organization has established vocational, trade, home-arts, and agricultural centres in various parts of the world, numerous high schools, schools of business administration, and charitable activities. Opus Dei also founded and endowed (with government assistance) the University of Navarra, which is regarded by many as Spain's finest university, and operates the Pontifical University of the Holy Cross in Rome and the University of Piura in Peru.