Papal primacy, also known as the primacy of the bishop of Rome, is a Roman Catholic ecclesiological doctrine concerning the respect and authority that is due to the pope from other bishops and their episcopal sees. The doctrine is accepted at a fundamental level by both the Catholic Church and Eastern Orthodox Church, though the two disagree on the nature of primacy.

English academic and Catholic priest Aidan Nichols wrote that "at root, only one issue of substance divides the Eastern Orthodox and the Catholic Churches, and that is the issue of the primacy." French Eastern Orthodox researcher Jean-Claude Larchet wrote that, together with the Filioque controversy, differences in interpretation of this doctrine have been and remain the primary causes of schism between the Catholic Church and the Eastern Orthodox Church. In the Eastern Orthodox churches, some understand the primacy of the bishop of Rome to be merely one of greater honour, regarding him as primus inter pares ("first among equals"), without effective power over other churches. Other Orthodox Christian theologians, however, view primacy as authoritative power: the expression, manifestation and realization in one bishop of the power of all the bishops and of the unity of the Church.

The Catholic Church attributes to the primacy of the pope "full, supreme, and universal power over the whole Church, a power which he can always exercise unhindered," a power that it attributes also to the entire body of the bishops united with the pope. The power that it attributes to the pope's primatial authority has limitations that are official, legal, dogmatic, and practical.

In the Ravenna Document, issued in 2007, representatives of the Orthodox Church and the Catholic Church jointly stated that both East and West accept the bishop of Rome's primacy at the universal level, but that differences of understanding exist about how the primacy is to be exercised and about its scriptural and theological foundations.

The Eastern Orthodox Church is opposed to the Roman Catholic doctrine of papal supremacy and infallability. While not denying that primacy does exist for the Bishop of Rome, Eastern Orthodox Christians argue that the tradition of Rome's primacy in the early Church was not equivalent to the current doctrine of supremacy. (Wikipedia)