ecumenical council of the Roman Catholic church (1438–45) in which the Latin and Greek churches tried to reach agreement on their doctrinal differences and end the schism between them. The council ended in an agreed decree of reunion, but the reunion was short-lived. The Council of Ferrara-Florence was not a new council but was the continuation of the Council of Basel (Basel, Council of), which Pope Eugenius IV transferred from Basel and which opened in Ferrara on Jan. 8, 1438. The Greek delegation, numbering about 700, included the patriarch of Constantinople Joseph II, 20 metropolitans, and the Byzantine emperor John VIII Palaeologus.

Discussions were held on purgatory and on the phrase Filioque (“and from the Son”) of the Nicene Creed, which sets forth the doctrine that the Holy Spirit proceeds from both the Father and the Son. The Greeks held that the Spirit proceeds from the Father only and had refused to accept the Filioque.

On Jan. 10, 1439, the council was moved from Ferrara to Florence when a plague hit Ferrara. After much discussion, the Greeks agreed to accept the Filioque and also the Latin statements on purgatory, the Eucharist, and papal primacy. The decree of union between the two groups (Laetentur Caeli) was signed on July 6, 1439. After their return to Constantinople, many of the Greeks repudiated the reunion. Meanwhile, the Latins completed union agreements with certain other Eastern churches. No extant document records the closing of the council, which moved to Rome in September 1443.

Doctrinally, the council is of interest because of the exposition of the Catholic doctrines of purgatory and of the primacy and plenary powers of the pope set out in Laetentur Caeli. The decree for union with the Armenians contains a long exposition of sacramental theology.