A cardinal is a senior member of the clergy of the Catholic Church. As titular members of the clergy of the Diocese of Rome, they serve as advisors to the pope, who is the bishop of Rome and the visible head of the worldwide Catholic Church. Cardinals are chosen and formally created by the pope, and typically hold the title for life. Collectively, they constitute the College of Cardinals. The most solemn responsibility of the cardinals is to elect a new pope in a conclave when the Holy See is vacant. With a few historical exceptions, popes are elected from among the College of Cardinals.
During the period between a pope's death or resignation and the election of his successor, the day-to-day governance of the Holy See is in the hands of the College of Cardinals. The right to participate in a conclave is limited to cardinals who have not reached the age of 80 years by the day the vacancy occurs. With the pope, cardinals collectively participate in papal consistories, in which matters of importance to the Church are considered and new cardinals may be created. Cardinals of working age are also often appointed to roles overseeing dicasteries (departments) of the Roman Curia, the central administration of the Catholic Church.
Cardinals are drawn from a variety of backgrounds, being appointed as cardinals in addition to their existing roles within the Church. Most cardinals are bishops and archbishops leading dioceses and archdioceses around the world – often the most prominent diocese or archdiocese in their country. Others are titular bishops who are current or former officials within the Roman Curia, generally the heads of dicasteries and other bodies linked to the Curia. A very small number are priests recognised by the pope for their service to the Church. Canon law requires them to be generally consecrated as bishops before they are made cardinals, but some are granted a papal dispensation. There are no strict criteria for elevation to the College of Cardinals. Since 1917, a potential cardinal must already be at least a priest, but laymen have been cardinals in the past. The selection is entirely up to the pope, and tradition is his only guide.
As of 3 August 2026, there are 240 serving cardinals, of whom 116 are eligible to vote in a conclave to elect a new pope.
There is general disagreement about the origin of the term, but a chief consensus is that the Latin cardinalis comes from the term cardo (meaning 'pivot' or 'hinge'). It was first used in late antiquity to designate a bishop or priest who was incorporated into a church for which he had not originally been ordained. In Rome the first persons to be called cardinals were the deacons of the seven regions of the city at the beginning of the 6th century, when the word began to mean 'principal', 'eminent', or 'superior'.
The name was also given to the senior priest in each of the "title" churches (the parish churches) of Rome and to the bishops of the seven sees surrounding the city. By the 8th century the Roman cardinals constituted a privileged class among the Roman clergy. They took part in the administration of the Church of Rome and in the papal liturgy. By decree of a synod of 769, only a cardinal was eligible to become Bishop of Rome. Cardinals were granted the privilege of wearing the red hat by Pope Innocent IV in 1244.
In cities other than Rome, the name cardinal began to be applied to certain churchmen as a mark of honour. The earliest example of this occurs in a letter sent by Pope Zacharias in 747 to Pippin the Younger, ruler of the Franks, in which Zacharias applied the title to the priests of Paris to distinguish them from country clergy. This meaning of the word spread rapidly, and from the 9th century various episcopal cities had a special class among the clergy known as cardinals. The use of the title was reserved for the cardinals of Rome in 1567 by Pius V.
In 1059, five years after the East-West Schism, the right of electing the pope was reserved to the principal clergy of Rome and the bishops of the seven suburbicarian sees. In the 12th century the practice of appointing ecclesiastics from outside Rome as cardinals began, with each of them assigned a church in Rome as his titular church or linked with one of the suburbicarian dioceses, while still being incardinated in a diocese other than that of Rome.
The term cardinal at one time applied to any priest permanently assigned or incardinated to a church, or specifically to the senior priest of an important church, based on the Latin cardo ('hinge'), meaning 'pivotal' as in "principal" or "chief". The term was applied in this sense as early as the 9th century to the priests of the tituli (parishes) of the diocese of Rome.
In the year 1563, the Ecumenical Council of Trent, headed by Pope Pius IV, wrote about the importance of selecting good cardinals: "nothing is more necessary to the Church of God than that the holy Roman pontiff apply that solicitude which by the duty of his office he owes the universal Church in a very special way by associating with himself as cardinals the most select persons only, and appoint to each church most eminently upright and competent shepherds; and this the more so, because our Lord Jesus Christ will require at his hands the blood of the sheep of Christ that perish through the evil government of shepherds who are negligent and forgetful of their office."
The earlier influence of temporal rulers, notably the kings of France, reasserted itself through the influence of cardinals of certain nationalities or politically significant movements. Traditions even developed entitling certain monarchs, including those of Austria, Spain, and France, to nominate one of their trusted clerical subjects to be created cardinal, a so-called "crown-cardinal".
In early modern times, cardinals often had important roles in secular affairs. In some cases, they took on powerful positions in government. In Henry VIII's England, his chief minister was for some time Cardinal Wolsey. Cardinal Richelieu's power was so great that he was for many years effectively the ruler of France. Richelieu's successor was also a cardinal, Jules Mazarin. Guillaume Dubois and André-Hercule de Fleury complete the list of the four great cardinals to have ruled France. In Portugal, due to a succession crisis, one cardinal, Henry of Portugal, was crowned king, the only example of a cardinal-king (although John II Casimir Vasa was a cardinal from 1646 until he resigned in 1647, later being elected and crowned King of Poland, in 1648 and 1649, respectively).
While the incumbents of some sees are regularly made cardinals, and some countries are entitled to at least one cardinal by concordat (usually earning either its primate or the metropolitan of the capital city the cardinal's hat), almost no see carries an actual right to the cardinalate, not even if its bishop is a patriarch: the notable exception is the Patriarch of Lisbon who, by Pope Clement XII's 1737 bull Inter praecipuas apostolici ministerii, is accorded the right to be elevated to the rank of cardinal in the consistory following his appointment.
In 1059, Pope Nicholas II gave cardinals the right to elect the Bishop of Rome in the papal bull In nomine Domini. For a time this power was assigned exclusively to the cardinal bishops, but in 1179 the Third Lateran Council restored the right to the whole body of cardinals.
This council also established a two-thirds majority of the College of Cardinals as a requirement for a valid papal election.
In 1586, Pope Sixtus V limited the number of cardinals to 70: six cardinal bishops, 50 cardinal priests, and 14 cardinal deacons. The number of seventy was in reference to the Sanhedrin and to the seventy disciples. Pope John XXIII exceeded that limit citing the need to staff church offices. In November 1970, in Ingravescentem aetatem, Pope Paul VI established that electors would be under the age of 80 years. When it took effect on 1 January 1971, it deprived 25 cardinals of the right to participate in a conclave. In October 1975 in Romano Pontifici eligendo, he set the maximum number of electors at 120, while establishing no limit on the overall size of the college.