Dates of Holy Days of Obligation 2010 Friday, January 1, 2010 - Mary, Mother of God - obligation to attend Mass Thursday, May 13, 2010 - Ascension of the Lord - obligation to attend Mass  Sunday, August 15, 2010 - Assumption of Mary - obligation to attend Mass Monday, November 1, 2010 - All Saints - not a day of obligation Wednesday, December 8, 2010 - Immaculate Conception - obligation to attend Mass Saturday, December 25, 2009 - Christmas - always a holy day Mass Schedule for Holy Days Vigil           5:30           7:30 pm on the evening before the Holy Day Holy Day           6:30 am            9:00 am          12:10 pm            5:30 pm             7:30 pm