The hierarchy of the Catholic Church is composed of the pope, bishops, priests, and deacons. They are ordained and dedicated to ministry to the faithful. Through dioceses and parishes, they teach and confer the sacraments.

At the top of the hierarchy, which is essentially a pyramid, is the pope. As supreme pontiff and Bishop of Rome, the pope follows a tradition that dates back to St. Peter and the earliest days of the Church. The pope is believed to be infallible when speaking on matters of faith or morals, although he generally consults his advisory body, the College of Cardinals, before he makes a decision affecting the Church.

The hierarchical structure of the Church has existed in more or less the same form since the twelfth century, when Pope Gregory VII instituted many reforms that increased papal control over the Church as a whole. One of these primary reforms did away with lay investiture; that is, public officials and monarchs lost the right to invest a bishop in their diocese. From then on, only the pope had the right to appoint a bishop, and in turn the bishops reported only to the pope. Gregory's aim in passing this reform was to prevent secular control over the Church's properties and activities.

It was at about the same time that the Church began to recognize the power of Canon Law, which codified all the activities of the Church, covering questions ranging from who could administer a sacrament to how the pope was chosen. The Code of Canon Law functioned as a kind of constitution for the Church. It determined procedures that were to be followed in the governance of the Church and thus clearly structured and supported the framework of the hierarchy.

The College of Cardinals usually elects the pontiff from among their membership. Once the pope is chosen, he remains the head of the Catholic Church until his death. As well as being the chief bishop of the Roman Catholic Church, the pope is also a ruler of a city-state, Vatican City, which allows him to have independence from any earthly political jurisdiction.

Cardinals

In the actual governance of the Church, the next step down on the hierarchical pyramid are the cardinals, who have the authority to elect and advise the pope. All cardinals are ordained bishops. They keep their Episcopal sees, whether they are titular or residential (that is, whether they are bishops of an actual place, such as the archdiocese of Chicago, or honorary bishops, by title only), along with their responsibilities as bishops. There are three levels of cardinals:

• Cardinal bishops, or Episcopal cardinals

• Cardinal priests, or Presbyter cardinals

• Cardinal deacons, or diaconal cardinals

The cardinal bishops are the titular bishops of the seven titular suburban sees of Rome. They elect a dean and subdean from among their members. The dean presides over the college, with the subdean acting in his absence, making them the second- and third-highest ranking clerics in the Church.

Cardinal priests are the ordinary bishops of dioceses who have been made cardinals. Cardinal deacons are titular archbishops who work for the Roman Curia and who have been raised to the cardinalate. Together, the cardinals make up the Sacred College of Cardinals, which acts as an advisory body to the pope.

The Roman Curia

The cardinal bishops work full-time in the Roman Curia. The Curia is the central body of the Church, which is subdivided into departments that handle such matters as Canon Law, heresies, the election and governance of bishops and dioceses, administration of the sacraments, matters concerning religious orders, missionary work, rites and liturgies, ceremonies, and religious studies. Certain departments of the Curia also make decisions regarding special petitions to the Curia, such as annulment petitions.