A vigil mass is a religious service held during the night leading to a Sunday or other feast day in Christian liturgy). The term "vigil" comes from the Latin word "vigilia," which means "a night to watch". During the 3rd and 4th centuries, in addition to the celebration of Mass, it was customary to hold a vigil, a prayer service in three parts, as night-watches in preparation for the feast. Commenced in the evening, a vigil terminated only the following morning. Its liturgical was elastic, involving readings, singing of psalms, homilies, chants, and various prayers, followed by the Eucharistic service).

Today, a few solemnities have their own Vigil Mass, which is usually celebrated on the evening before the feast day. These solemnities are Easter Sunday, the Ascension of the Lord, Pentecost, the Nativity of St. John the Baptist, St. Peter & St. Paul, the Assumption of the Blessed Virgin Mary, the Nativity of the Lord, and the Epiphany of the Lord. The readings and prayers for these Masses are different from the texts of the Mass celebrated on the feast day. The Christmas Vigil Mass is celebrated on December 24, and it is often confused with the Christmas Midnight Mass. During the Christmas Vigil celebration, the faithful participate in an "anticipated celebration" of the Nativity of the Lord prior to midnight.

In a broader sense, the term "vigil Mass" is sometimes used to refer to a Mass held on Saturday evening, attendance at which fulfills ones obligation to attend Mass on Sunday).