This feast occurs on a Saturday this year, but it remains a Holy Day of Obligation. Masses taking place in the evening of December 8 should celebrate the Second Sunday of Advent. The faithful may be advised that there is a Mass obligation both for the Solemnity of the Immaculate Conception and the Second Sunday of Advent; that is, each day of obligation must be fulfilled with a separate Mass.
December 8: Solemnity of the Immaculate Conception
by Fr. Matthew Ernest | Nov 28, 2018