The Lateran Council of 649 was a synod held in the Basilica of St. John Lateran to condemn Monothelitism, a Christology espoused by many Eastern Christians, and Pope Honorius. The Council did not achieve ecumenical status in either East or West, but represented the first attempt of a pope to convene an ecumenical council independent of the Roman emperor.

According to Andrew Ekonomou, the irony of the council was that the denunciation of the theology of Constantinople came from the "collaboration of a Greco-Palestinian pope and a Constantinopolitan monk employing a style of theological discourse whose tradition was purely Eastern." Although Pope Martin I and Maximus the Confessor were abducted by Constans II and tried in Constantinople for their role in the council (Martin I being replaced as pope before dying in exile), their position was ultimately endorsed by the Third Council of Constantinople in 680.

Most members of the contemporary Roman clergy would have been too uneducated in theology to "grasp even the fundamental issues presented in the Monothelite controversy" due to centuries of decay in both religious and secular learning in the city. However, Rome had been the beneficiary of a brain drain of the Eastern empire, as Greek monks like Maximus the Confessor fled from Africa and the Middle East to Rome. Although the position of the council was substantially similar to that espoused by the Council of Chalcedon, "for the first time in well over a century, the church of Rome would be in a position to debate theological issues with Byzantium from a position of equality in both intellectual substance and rhetorical form."

The synod has its roots in a series of correspondence between Pope Theodore I and Maximus dating to 646, before the latter's arrival in Rome. The momentum for the council was almost extinguished when Patriarch Pyrrhus of Constantinople in late 646/early 647 denounced Monothelitism before the Roman clergy and laity. However, Pyrrhus changed his mind upon leaving Rome and arriving in Ravenna, and his successor Paul II of Constantinople was of the same mind.

Emperor Constans II issued the Typos in 648 which prohibited any discussion of the issue of "one will and one energy, or two energies and two wills" in Christ. The Typos was viewed as an unacceptable threat to the legacy of Chalcedon, and thus hardened the determination of Theodore and Maximus to convene a council. Maximus and other monks from his order did all the "planning, preparation, and scripting" of the council. In contrast, there is little evidence that Pope Theodore did much to prepare for the council.

Maximus and Theodore did not regard the council as merely a meeting of the Roman church, but rather one "in the nature of a general or ecumenical council." In a letter to a Cypriot priest, Maximus referred to the council as the "sixth synod, which through the divine inspiration of God set forth with all pure piety the doctrines of the holy Fathers."

Never before had the pope—or any prominent Christian leader—challenged the authority of the Roman emperor alone to convene an ecumenical council. Even Athanasius, the virulent opponent of Constantius II's Arianism, had conceded this to the emperor he regarded as a heretic. The papacy also had long regarded ecumenical councils as the prerogative of the emperor; for example, when Pope Julius I convened a synod to rehabilitate Athanasius (condemned by the First Synod of Tyre), he defended the practice by claiming the synod was not meant to be general or ecumenical. Although the Council planned to send its canons to Constans II for ratification, there was little doubt that this would be viewed as "form without substance." Theodore and Maximus were undoubtedly aware that they were "claiming nothing less than a revolutionary role for the Papacy."

Later popes would de facto repudiate this usurpation by allowing the emperor to convene the Third Council of Constantinople (680). Nevertheless, the Lateran Council of 649 constituted a watershed moment in the history of the primacy of the Roman pontiff. In an attempt to legitimize the council, neither Maximus nor Theodore attempted to innovate further with its methodology.