Gregorian Masses are a series of thirty Masses celebrated on thirty consecutive days for the repose of the soul of a departed person. Gregorian Masses derive their name from Pope Saint Gregory the Great, who was the first to popularize this practice. It is related in the Dialogues of Saint Gregory that the soul of a departed Monk appeared and declared that he had been delivered from Purgatory at the completion of thirty Masses. The Sacred Congregation of Indulgences has declared the tradition to be "a pious and reasonable belief of the faithful."
The Offering for Gregorian Masses is $200.