In addition to Sunday, Mass attendance is required on Holy Days of Obligation.
The days to be observed as Holy Days of Obligation in the Latin Rite Dioceses of the United States of America, in conformity with Canon 1246, are as follows:
Thursday, August 15th - Assumption of Mary
Friday, November 1st - All Saint's Day
Monday, December 8th - The Immaculate Conception of the Blessed Virgin Mary
Wednesday, December 25th - Christmas
When January 1st (Mary, Mother of God), August 15th (Assumption of the Blessed Virigin Mary), or November 1st (All Saints) fall on a Saturday or Monday, the precept to attend Mass is abrogated.