The Solemnity of Our Lord Jesus Christ, King of the Universe, commonly referred to as the Feast of Christ the King, Christ the King Sunday of Reign of Christ Sunday, is a relatively recent addition to the Western liturgical calendar, having been instituted in 1925 by Pope Pius XI for the Roman Rite of the Catholic Church. In 1970 its Roman Rite observance was moved to the final Sunday of Ordinary Time. Therefore, the earliest date on which it can occur is 20 November and the latest is 26 November.
Roman Catholics adhering to the Extraordinary Form of the Roman Rite use the General Roman Calendar of 1960, and as such continue to observe the Solemnity on its original date of the final Sunday of October.