The fourth Sunday of Lent in the Roman Catholic liturgical calendar. The term is derived from the opening words of the Latin Mass, "Rejoice (Laetare) Jerusalem" (Is 66:10). The church is called to joyful anticipation of the victory to be won. This joyful theme provides lightening from the penitential emphasis of Lent. Since the thirteenth century the celebrant of the eucharist has been permitted to wear rose-colored vestments which express the change of tone in the Lenten observance. Laetare Sunday therefore may be called "Rose Sunday." This custom is not required in the Episcopal Church, but it is observed by some parishes with a traditional Anglo-catholic piety. See Gaudete Sunday.