1536 - Holy Orders is the sacrament through which the mission entrusted by Christ to his apostles continues to be exercised in the Church until the end of time: thus it is the sacrament of apostolic ministry. It includes three degrees: episcopate, presbyterate and diaconate.

1554 - The divinely instituted ecclesiastical ministry is exercised in different degrees by those who even from ancient times have been called bishops, priests and deacons. Catholic doctrine, expressed in the liturgy, the Magisterium and the constant practice of the Church, recognizes that there are two degrees of ministerial participation in the priesthood of Christ: the episcopacy and the presbyterate. The diaconate is intended to help and serve them. For this reason the term sacerdos in current usage denotes bishops and priests but not deacons. Yet Catholic doctrine teaches that degrees of priestly participation (episcopate and presbyterate) and the degree of service (diaconate) are all three conferred by a sacramental act called "ordination," that is, by the sacrament of Holy Orders.

1576 - Since the sacrament of Holy Orders is the sacrament of the apostolic ministry, it is for the bishops as the successors of the apostles to hand on the "gift of the Spirit", the "apostolic line." Validly ordained bishops, i.e. those who are in the line of apostolic succession, validly confer the three degrees of the sacrament of Holy Orders."

1577 - "Only a baptized man validly receives sacred ordination." The Lord Jesus chose men to form the college of the twelve apostles, and the apostles did the same when they chose collaborators to succeed them in their ministry. The college of bishops, with whom the priests are united in the priesthood, makes the college of the twelve an ever-present and ever-active reality until Christ's return. The Church recognizes herself to be bound by this choice made by the Lord himself, For this reason the ordination of women is not possible."