The Chaldean Catholic Church is descendant from the Church of the East, an Ancient Church located in Mesopotamia that can trace her roots to Mar Addai (St. Addai) and Mar Mari (St. Mari), disciples of St. Thomas the Apostle. Today, four churches claim patrimony from the Church of the East: The Chaldean Catholic Church, The Assyrian Church of the East, The Ancient Assyrian Church of the East, and The Syro-Malabar Church.
The Catholic Church is composed of various Rites, both Western and Eastern Rites. There are 23 Eastern Rites, of these the Chaldean Catholic Church is one of them. To be an Eastern Rite means that the Church retains her identity and tradition, liturgical, spiritual, etc., but has full communion with the Pope of Rome.
The Patriarchate of the Chaldean Catholic Church currently resides in Baghdad, Iraq, with Eparchies (Dioceses) around the world. The largest population of Chaldean Catholics found outside the Middle East is located in Michigan, U.S.A. The cathedral parish St. Thomas the Apostle Chaldean Catholic Eparchy of the U.S.A. is Mother of God Cathedral, located in Southfield, Michigan.