January 1 is the Solemnity of Mary, the Mother of God. It is a Holy Day of Obligation. However, when it falls on a Saturday or a Monday, the obligation to attend Mass is abrogated.
We celebrated the liturgical feast of the Blessed Virgin Mary on January 1st, which is the Octave of Christmas. Only Christmas and Easter enjoy the privilege of an octave, which is an eight-day extension of the feast. The honoring of Mary as the Mother of God can be traced back to the Council of Ephesus in 431. By the 7th century, January 1st was observed as a celebration of the Maternity of the Blessed Virgin Mary. In the 13th century, the Feast of the Circumcision of Christ had come to replace the feast honoring Mary; however in 1751, after a push in Portugal for an official feast day celebrating Mary’s divine maternity, Pope Benedict XIV allowed Portugal’s churches to devote a feast to Mary on the first Sunday in May. Eventually, the feast extended to other countries, and in 1914 began to be observed on October 11. In 1931, Pope Pius XI extended the feast to the entire church, and in 1974, Pope Paul VI removed the feast of the Circumcision of Christ from the liturgical calendar and replaced it with the feast of the “Solemnity of Mary, Mother of God”, bringing Mary’s feast day back to the first day of the year.