Is It Common For Catholic Priests To Deny Parishioners Communion At Mass?

It is very uncommon for a Catholic priest to deny a parishioner, or anyone else communion during Mass. Catholics attending Mass are expected to judge for themselves if they are in a state of grace and thus in a position to receive communion in good conscience.

It should also be noted that the way in which parishioners participate in communion varies from one parish to another. In many cases, the faithful will line up in front of the altar, while in others cases they may kneel along the rail surrounding the altar. In an increasing number of cases, however, parishioners may simply pass the wafers and the wine to each other and will not have to rise from their seat. In this case, of course, the priest will have very little control over who receives communion.

In rare cases, a priest might discourage someone from receiving communion, if  he know that the person is in a state of mortal sin, or if the person is a non-Catholic. As the Catholic Church has a policy of  "Closed Communion" non-Catholics should not generally participate in the Eucharist.