The First Council of the Lateran was summoned by Pope Calixtus II in 1123. It was the 9th ecumenical council of the Roman Catholic Church. The key issue was to end the Investiture Controversy by confirming the Concordat of Worms (1122). The council lasted from March 18th to 27th.
It was held in the Lateran Palace, Rome, and was the first Church council held in western Europe (see the Great Schism). At least 300 western church leaders attended, and possibly as many as a thousand.
Beyond the key issues from the Concordat of Worms (the state role in the investiture of prelates and freedom of the church) the council promulgated canons relating to reform of church discipline and the control of ecclesiastical abuses, the abolition of simony, and it set the grounds for the crusades to recover the Holy Land. There were 22 disciplinary canons promulgated, forming the basis of medieval Church law.