It is headed by a Catholicos (the plural is Catholicoi). It is traditional in Eastern churches for the supreme head of the church to be named 'Patriarch', but in the Armenian Apostolic Church hierarchy, the position of the Catholicos is higher than that of the Patriarch. The Armenian Apostolic Church presently has two catholicoi (Karekin II, Supreme Patriarch and Catholicos of All Armenians, and Aram I, Catholicos of the Great House of Cilicia), and two patriarchs, plus primates, archbishops and bishops, lower clergy and laity serving the Church.
