Ferias are those days of the week on which neither a Feast nor a Vigil is celebrated. The Mass of the previous Sunday is offered except when that day has a Mass of its own as in Lent and on the Ember Days.

On Ferias of the 4th class, the priest has the option of saying a Votive Mass (in honor of some mystery of Our Lord or the Blessed Virgin Mary, in honor of one of the Saints, or for a special intention) or he may offer a Requiem Mass.