The Solemnity of the Immaculate Conception of the Blessed Virgin Mary, which celebrates the dogma that Mary was preserved from original sin from the moment of her conception, will be celebrated Dec. 8. The feast day is a holy day of obligation on which Catholics are required to attend Mass.

In 1846, while meeting in Baltimore, the U.S. bishops adopted a decree naming Mary, “conceived without sin,” as patroness of the United States. Pope Pius IX approved the choice and placed the United States under the patronage of the Immaculate Conception in 1857.