Any Catholic may offer up the Mass in which he or she participates for any good intention. Certainly, graces will accrue in accordance with the intensity of that person's participation and sincerity.  This is a genuine exercise of the royal or common priesthood of the faithful.

However, the custom of requesting a priest to offer the Mass for a specific intention, even when one cannot be physically present at the Mass, is a long standing tradition in the Church.  This is because the Church considers the Mass as the greatest possible prayer of intercession insofar as it is the perfect offering of Christ to the Father by making present the paschal mystery of his death and resurrection.

Because of the particular role of the priest as mediator between God and man, acting in persona Christi when offering the holy sacrifice of the Mass, it is usually considered that special graces may be obtained when he applies the Mass to a particular intention.

The faithful generally make an offering, called a stipend, to the priest in order to apply the Mass to a specific intention. By making this offering, the faithful, by parting with something that is their own, associate themselves more intimately with Christ who offers himself in the sacred Host, and obtain thereby more abundant fruits (See Pope Paul VI's letter Firma in Traditione of June 13, 1974).

This sacrifice has an infinite value and indeed there is no objective limitation to the number of intentions that can be offered at any Mass. The offering of a stipend is also a means whereby Catholic may contribute to the upkeep of the clergy, and the Church in general.

In order to grasp the issues involved, it may help to realize what happens when a priest, or his representative, accepts a stipend to have a Mass said for a specific person or intention.   The person who has offered the stipend has not "bought a Mass," a thing which is patently impossible. What has happened is that the priest has committed himself to celebrate a Mass according to the intentions of the person making the offering. This intention is most often to recommend the soul of a deceased person but may also be for the personal intentions of the living.

Because the intention is essentially a spiritual act, its publication neither adds nor subtracts from its efficacy. Indeed, publicly announcing the intention is done for the comfort of the living and not for the benefit of the dead.

-Fr. Edward McNamera