The Immaculate Conception is a Holy Day of Obligation recognizing the belief that Mary was without the stain of original sin from the moment of her conception, making her perfection as the Mother of God. Because the Holy Day falls on a weekend there will be a Vigil Mass on Friday, December 7th at 7:00 p.m. and Mass on Saturday, December 8th at 10:00 a.m. This is a separate obligation than that of Sunday Mass, i.e. the faithful are expected to attend Mass in observance of the Holy Day on the 7th or in the a.m. of the 8th, and still attend regular 4:00 Saturday or Sunday morning services.