The Mass for December 24 is the proper text for Masses in the morning of December 24. The proper text for Masses in the evening (= after 4 p.m.) of December 24 is the Christmas – Vigil Mass. The text for Christmas – Mass during the Night is to be used for Masses beginning “at night,” preferably on or around midnight between December 24 and 25. The proper text for the first Mass in the morning of December 25 is the Christmas – Mass at Dawn. Later Masses on December 25 should use the text for Christmas – Mass during the Day.
 
According to the Lectionary for Mass, for the three Masses of Christmas (Night, Dawn, Day), the proper readings for the Mass may be used or the readings may be chosen from among any of the readings for Christmas or the Vigil—based on pastoral need. Pastors should carefully discern those needs before selecting readings other than those proper to each Mass. Only the Vigil readings may be used at the Vigil Mass. The Mass during the Night may be preceded by a more prolonged vigil, taken from the Office of Readings (see the General Instruction of the Liturgy of the Hours #71-73, 98, 215). This extended vigil is the preferred time for the blessing of the crèche (Book of Blessings, ch. 48, §1542-44).