All Catholics, both women and men, are called by virtue of their baptism to give witness to the gospel of Jesus Christ in the wider world and at the same time, use their unique gifts, talents, and charisms to build up the Church, the Body of Christ.

Holy Orders is the Sacrament through which the mission entrusted by Christ to the apostles continues to be exercised in the Church until the end of time: thus it is a Sacrament of apostolic ministry. It is a ministry of service to the wider community of the baptized. It includes three degrees: episcopate (bishops), presbyterate (priests) and diaconate (deacons).

Priests are usually unmarried (celibate) men who exercise their ministry within a parish community. Their ministry is one of building up the community of faith through the proclamation of the Word of God, celebrating the Sacraments (especially the Mass) and facilitating the various ministries within a parish community.

Bishops are chosen from among priests to lead a specific geographical area comprised of many parishes. It is the bishop's responsibility to offer pastoral care to his diocese and maintain unity with the wider Church, especially with the successor to Saint Peter, the Pope.

Deacons are men, both married and unmarried, who serve as ministers of the Sacraments of Baptism and Marriage. They assist in the celebration of Mass, especially through the proclamation of the Gospel and sometimes the homily. Deacons are called to a special service to the poor and needy of the community.

Un-ordained men and women also serve the Church through ministries of service and leadership as religious sisters and brothers. Those serving in this capacity join a specific community or religious congregation. Many of these communities focus on a specific kind of ministry to the wider Church (e.g. teaching, care of the aged, etc.)