The Ecumenical Patriarchate of Constantinople is one of the most enduring institutions in the world and has had a prominent part in world history. The ecumenical patriarchs in ancient times helped in the spread of Christianity and the resolution of various doctrinal disputes. In the Middle Ages they played a major role in the affairs of the Eastern Orthodox Church, as well as in the politics of the Orthodox world, and in spreading Christianity among the Slavs. Currently, in addition to the expansion of the Christian faith and the Eastern Orthodox doctrine, the patriarchs are involved in ecumenism and interfaith dialogue, charitable work, and the defense of Orthodox Christian traditions.
Within the five apostolic sees of the Pentarchy, the Ecumenical Patriarch is regarded as the successor of Andrew the Apostle. The current holder of the office is Bartholomew I, the 270th bishop of that see.
The Ecumenical Patriarch of Constantinople is first among equals, or first in honor among all Eastern Orthodox bishops, who presides in person—or through a delegate—over any council of Orthodox primates and/or bishops in which he takes part and serves as primary spokesman for the Orthodox communion, especially in ecumenical contacts with other Christian denominations. He has no direct jurisdiction over the other patriarchs or the other autocephalous Orthodox churches, but he, alone among his fellow-primates, enjoys the right of convening extraordinary synods consisting of them and/or their delegates to deal with ad hoc situations and has also convened well-attended Pan-Orthodox Synods in the last forty years. His unique role often sees the Ecumenical Patriarch referred to as the spiritual leader of the Orthodox Church in some sources, though this is not an official title of the patriarch nor is it usually used in scholarly sources on the patriarchate. The Orthodox Church is entirely decentralized, having no central authority, earthly head or a single Bishop in a leadership role, having synodical system canonically, is significantly distinguished from the hierarchically organized Catholic Church whose doctrine is the papal supremacy. His titles primus inter pares "first among equals" and "Ecumenical Patriarch" are of honor rather than authority and in fact the Ecumenical Patriarch has no real authority over Churches other than the Constantinopolitan.
The Ecumenical Patriarch of Constantinople is the direct administrative superior of dioceses and archdioceses serving millions of Greek, Ukrainian, Rusyn and Albanian believers in North and South America, Western Europe, Australia and New Zealand, Korea, as well as parts of modern Greece which, for historical reasons, do not fall under the jurisdiction of the Church of Greece.
The Orthodox Church in America, while acknowledging the Ecumenical Patriarch's role in "guiding and preserving the worldwide unity of the family of self-governing Orthodox Churches", also emphasizes that he carries no sacramental or juridical power over bishops outside of his own Patriarchate, and further states that "it is possible that in the future this function may pass to some other church."