Immaculate Conception

The Immaculate Conception is a Catholic Solemnity celebrating Mary’s conception without sin on December 8. This Holy Day of Obligation occurs during Advent which is the season of preparation for the birth of Our Lord Jesus Christ, however, the Immaculate Conception actually refers to the conception of Mary in the womb of her mother, St. Anne, nine months before Mary’s Nativity, celebrated on September 8.