Eastern Orthodoxy by country
Based on the numbers of adherents, the Eastern Orthodox Church (also known as Eastern Orthodoxy) is the second largest Christian communion in the world after the Roman Catholic Church. The most common estimates of the number of Eastern Orthodox Christians worldwide is approximately 200–260 million. The numerous Protestant groups in the world, if taken all together, outnumber the Eastern Orthodox, but they differ theologically and do not form a single communion.
Orthodox Church in America
In 2000, a study by Alexei D. Krindatch, of the Patriarch Athenagoras Orthodox Institute, presented a substantially lower figure—115,100 adherents (baptized Orthodox who attend services on at least an occasional basis and their children) and 39,400 full members (persons older than 18, paying annual Church membership fees). The Greek Orthodox Archdiocese, by comparison, was listed as having 440,000 adherents. In response to the study, an OCA representative stated the Church had "around 750,000 adults and children."