The Solemnity of the Immaculate Conception of the Blessed Virgin Mary will be transferred to Monday, Dec. 9, 2024. The Holy See informed the U.S. Bishops that the obligation is also transferred. This is also the patronal feast of the Catholic Church in the United States of America. Here is the link to the previous explanation of this change: tinyurl.com/HolyDay2024 (case sensitive).