Q.     Is it appropriate to go to confession during a Mass in which I’m participating?  Should parishes be offering the Sacrament of Penance while Mass is taking place in the same church?

A.     Generally, no. In earlier liturgical practice, confessions were routinely heard during Mass. This was possibly due to the fact that the accepted norm prior to the liturgical reform of St. Paul VI saw one's obligation to assist at Mass fulfilled by attending from the Offertory of the Mass onward and thus the faithful often engaged in other liturgical and devotional practices up to that point of the Mass (including praying the rosary, reading their own devotional texts, and – yes – going to confession.)

There is no prohibition strictly speaking about the Sacrament of Penance being offered at the same time as Mass, though the Rite of Penance does state that "[The faithful] should be encouraged to approach the Sacrament of Penance at times when Mass is not being celebrated" (n. 13).  This has a practical value in that everyone who is participating in Mass should not be distracted by anything else, including the Sacrament of Penance. Therefore, it is highly laudable that only those NOT participating in Mass should be celebrating the Sacrament of Penance while Mass is going on. The idea of “2-for-1,” i.e. going to confession while the Mass I’m participating in is happening, is not ideal and detracts from the vision of the General Instruction of the Roman Missal that says that "the entire celebration [of the Mass] is arranged in such a way that leads to a conscious, active, and full participation of the faithful, namely, in body and in mind, a participation fervent with faith, hope, and charity, of the sort which is desired by the Church and which is required by the very nature of the celebration and to which the Christian people have a right and duty in virtue of their Baptism" (n. 18).  

So, if confessions are regularly scheduled during Mass (a practice to be discouraged for the above reasons), catechesis should be provided to ensure the faithful know that confession should precede Mass whenever possible, and not take place while they are participating in Mass to fulfill their Sunday obligation.