Once for the Fourth Sunday of Advent:
December 23rd in the evening (5:30pm -English or 7:00pm -Spanish) or December 24th in am (9:00am – English)
Again for Christmas Mass: December 24th in the evening (5:30pm – English, 7:00pm -Spanish, 10:00pm- English) or December 25th (9:00am – English)
There is an obligation to participate at Mass for both the Fourth Sunday of Advent and for Christmas this weekend.
Attendance at one Mass does not fulfill both obligations.