The Mass of the catechumens consisted of psalms and lessons from the Scriptures.

The African Church seems to have divided the Mass into the Mass of the catechumens, and the Mass of the faithful.

The Mass of the Catechumens is almost identical, with of course appropriate Collects, psalms, Litanies, and Lections.

This ancient custom is still evident in the extraordinary form of the Roman Rite, where the Mass is divided into two parts; the Mass of the Catechumens, and the Mass of the Faithful.

It was originally called the Mass of the Catechumens, because the Catechumens, or candidates for Baptism, were required to leave the ceremony before the beginning of the Liturgy of the Eucharist, or Mass, proper.