He called the organization Opus Dei to emphasize his belief that its foundation was a "work of God,"- or, in Latin, "Opus Dei."
The organization began as a program of Catholic spiritual and intellectual formation for laymen, and began admitting women to its programs of formation two years after its foundation.
Technically, Opus Dei is a "personal prelature," which, canon law says, is a Church structure which "consists of presbyters and deacons of the secular clergy" joined together to "accomplish particular pastoral or missionary works," according to canon law. The priests and deacons of the prelature are not members of a religious order, like the Jesuits or Benedictines, and therefore, they do not make public vows of poverty, chastity, and obedience, as religious priests and brothers do. Instead, they are secular clerics, as are diocesan priests, which means that like diocesan priests, they are obliged to celibacy and to obedience, but they are not bound to poverty, or to other aspects of monastic, or religious life.
Opus Dei's work and structure also involves lay Catholics, who associate themselves to the mission of the prelature by means of individual agreements, as defined by the organization's statutes, or governing documents. In fact, the majority of those involved in the work and mission of Opus Dei are lay people.
Lay association comes at different levels: some unmarried Catholics collaborate with Opus Dei as "numeraries," who dedicate much of their life and time to Opus Dei and its mission; "supernumeraries" are typically married, and share in Opus Dei's work and mission in the context of their families; "associates" are celibate collaborators who do not reside in Opus Dei centers; "cooperators" may be married or unmarried laity who collaborate with or support Opus Dei at a less committed level. There are also diocesan priests and bishops associated with Opus Dei through an organization called the Priestly Society of the Holy Cross.
While they are formally connected to the prelature, numeraries, supernumeraries, and cooperators remain subject to the jurisdiction of their own diocesan bishops and pastors. The prelate, or head, of Opus Dei does not exercise ecclesiastical jurisdiction for those collaborators, except in regard to specifically delineated matters related to collaboration in the prelature's mission. The educational and spiritual work of Opus Dei, including formation, is subject to the oversight of the diocesan bishop in each place where the prelature operates.