The Synod of Jassy or Synod of Ia?i (also referred to as the Council of Jassy or the Council of Ia?i), was convened in Ia?i in Moldavia (present day Romania) between 15 September and 27 October 1642 by the Ecumenical Patriarch Parthenius I of Constantinople, with the support of the Moldavian Prince Vasile Lupu.
The purpose of the synod was to counter certain Roman Catholic and Protestant "doctrinal errors" which had made inroads into Orthodox Christian theology and to offer a comprehensive Orthodox statement on the content and character of the faith. Including representatives of the Greek and Slavic Churches, it condemned the Calvinist teachings ascribed to Cyril Lucaris and ratified (a somewhat amended text of) Peter Mogila's Expositio fidei (Statement of Faith, also known as the Orthodox Confession), a description of Christian orthodoxy in a question and answer format. The Statement of Faith became fundamental for establishing the Orthodox world's attitude toward Reformation thought. The major contribution of the synod was the reinforced sense of unity in the Orthodox Church through the promulgation of an authoritative statement agreed upon by all the major sees.