Their main ceremony is the Mass. Catholics are normally required to go to amass on Sundays and on Holy Days of Obligation. In the United States, the Holy Days of Obligation are: Mary, Mother of God (January 1), The Assumption of Mary (August 15), The Immaculate Conception (of Mary) (December 8), The Ascension of Jesus (40 days after Easter), Christmas (December 25) and All Saints Day (November 1). The taking of the Eucharist is the height of the Mass.