Eleven councils of great historical importance have been held in the Lateran basilica, of which the five following are considered by Roman Catholic jurists as oecumenical.

I. The Ninth Oecumenical

I. The Ninth Oecumenical (or the tenth, if the council of Jerusalem is included in the list) and the first general council held in the West, convened by Calixtus II., who presided over it. It opened March 18, and closed April 5, 1123. There were present 300 archbishops and bishops, and 600 inferior prelates. The chief object of the convocation was to terminate the long quarrel about investitures by promulgating the concordat concluded at Worms between the pope and the emperor Henry V., Sept. 23, 1122. In this it was stipulated: 1, that elections to ecclesiastical dignities in Germany should be held in presence of the emperor or his delegates, without violence or simony, and that the prelate elect should receive by the delivery of the sceptre, the symbol of temporal rule, the investiture of his temporalities; 2, that the emperor renounce all claim to invest with the ring and crosier, the symbols of spiritual jurisdiction; 3, that the emperor grant to all churches within his domains perfect freedom in canonical elections, and pledge himself to protect the Roman see against all enemies.

Twenty-two canons were also published against simony, concubinage, and all who coin or circulate counterfeit money.

II. The Tenth General Council

II. The Tenth General Council, convened by Innocent II., who presided over it. It opened April 20, 1139. About 1,000 prelates were present. It condemned the antipope Anacletus II. and his chief supporter, Roger II. of Sicily, and anathematized the doctrines and adherents of Arnold of Brescia, of Peter de Bruys, and of the Manichaean heresy.

III. Convened By Alexander III

III. Convened By Alexander III. to give effect to the peace concluded at Venice between himself and Frederick I. in 1177. Three sessions were held, March 2, 14, and 19, 1179, and 27 canons were enacted. It was decreed that in papal elections a two-thirds vote of all the cardinals assembled should be necessary for a valid choice; that no candidate for the episcopal office could be validly chosen till he had completed his 30th year, and that he must be born in lawful wedlock, and of blameless life and doctrine; that for inferior ecclesiastical dignities the candidate must be 25 years of age, and receive holy orders within a specified time, under pain of forfeiture; that no money or presents should be either asked or accepted for the consecration of prelates, or their installation, for marriage or funeral fees, or for the administration of any sacrament; that in all cathedrals and principal churches masters should be maintained to teach gratuitously, and free schools should be opened in all churches and monasteries where a provision for free education had formerly been made.

Tournaments at fairs are forbidden; the "truce of God" must be strictly observed; lepers must be carefully provided for, churches, cemeteries, and priests must be set apart for them, and they shall be exempt from taxation and all other public burdens. The 27th canon anathematizes the Catharists and Waldenses.

IV. The Fourth Lateran Council

IV. The Fourth Lateran Council is thought to be the most important ecclesiastical assembly ever held in Christendom. It was convened by Innocent III., opened Nov. 11, 1215, and closed Nov. 30, although sessions were held in January, 1216. Innocent III. presided. There were present 71 archbishops, 412 bishops, 800 abbots, three eastern patriarchs, with the representatives of the others, and the ambassadors of all the Christian sovereigns. In the first session a solemn profession of faith was presented by the pope and accepted. In it the term "transubstantiation" was first used regarding the change in the eucharistic bread and wine. All heresies contrary thereto were anathematized; and it was decreed that all known heretics, after their condemnation by an ecclesiastical tribunal, should be delivered over to the secular arm; all abettors of heresy are excommunicated, and all dignitaries who do not use their endeavors to rid their domains of heretics are threatened with the same penalty. Next come decrees tending to conciliate the eastern churches, and establishing the order of precedence between the great patriarchates.

Bishops are enjoined to reform all abuses and scandals among clergy and laity; and they are to choose none but edifying ministers of God. The decrees about free schools in the principal churches are renewed, and to them is added the obligation of maintaining gratuitous courses of instruction in theology and Scripture. New canons prescribe the obligation incumbent on all without exception of confessing their sins once a year and receiving the eucharist at Easter. Marriage is forbidden between persons related in the first four degrees of consanguinity. The canons regulating ecclesiastical elections are insisted on, the existing religious orders are to be strictly reformed, and no new ones introduced. The last and most earnest measures of the council and the presiding pontiff were taken for the relief of Palestine. It was agreed by the representatives of the Christian powers that the crusading armies should rendezvous at Brindisi and Messina on June 1, 1217. Meanwhile bishops and priests were to preach the crusade unceasingly.

The pope bound himself to limit his personal expenses, and to furnish 30,000 livres as his first contribution; the clergy were to give the 20th part of their income for three years, and the cardinals the 10th, under pain of excommunication.

V. Reckoned As The Nineteenth Oecumenical Council

V. Reckoned As The Nineteenth Oecumenical Council, convened by Julius II. for the purpose of counteracting the influence of the schismati-cal assemblage called in Pisa in 1511 by a portion of the cardinals acting under the orders of the emperor Maximilian and of Louis XII. of France. The council was opened May 3, 1512, by Julius in person. There were present in the first session 15 cardinals, the patriarchs of Alexandria and Antioch, 10 archbishops and 56 Italian bishops, a large number of inferior prelates, and the ambassadors of Spain, Venice, and Florence. Later the other sovereigns sent their representatives, and permitted their subject bishops to attend the council. On May 17 articles of confederation between the pope and the king of England were read. In the session of Dec. 3 France was laid under an interdict. The pope, whose health was failing, promulgated a decree about papal elections, excluding the council from all participation therein, and invalidating every choice made by the cardinals under the influence of simony, even when followed by coronation and recognition by the states of Christendom. Leo X. presided over the last sessions of the council, in which the schismatic cardinals were reconciled to the church, and a bull was read Dec. 19, 1516, condemning the pragmatic sanction of Charles VII. of France, and substituting therefor a concordat concluded with Francis I. The council was closed March 16, 1517. - The dates and principal acts of the Lateran councils not considered general were as follows: 1. Convened Oct. 5, 649, concluded Oct. 31, under Martin I. There were 500 bishops present.

The Monothelite heresy, the Ecthesis of Sergius of Constantinople (639), and the Typus of the emperor Constans II. (648), were condemned. 2. Convened Dec. 23, 864, by Nicholas I., and concluded in January, 865. It condemned Rodoald, bishop of Porto, and Zachary, bishop of Anagni, papal legates in Constantinople, for supporting the intrusion of Photius in 861. 3, 4, and 5, in 1105, 1111, and 1112, respectively, were convened by Paschal II. during his quarrel about investitures with the emperor Henry V. 6. Convened in March, 1167, by Alexander III., to excommunicate and depose the emperor Frederick I. Two other convocations, reckoned as councils by some authors, were held in the Lateran respectively in 900, to annul the sentence of deposition on Aargrine, bishop of Langres, and in 993, to celebrate the first known solemn canonization, that of St. Udalric, bishop of Augsburg.