In the Eucharistic Prayer, after the invocation of the Holy Spirit to effect transubstantiation and the Words of Institution, the priest invites the congregation to recite the Memorial Acclamation with the words "Mystery of Faith." This phrase and the Memorial Acclamation that follows are often sung or chanted.
There are four forms of the Memorial Acclamation in the present English translation of the Roman Missal:
The first two English acclamations are departures from the Latin typical edition of the Roman Missal. The first was a preexisting composition adopted in lieu of a translation of the first Latin acclamation, and the second was a new composition, derived from wording found in the first Easter Preface.
In Canada each acclamation is introduced with a unique introduction:
The French translation also has unique introductions, the second of which appropriates part of the Latin acclamation.
After the Memorial Acclamation is recited or sung, the Eucharistic prayer continues with the anamnesis.
Prior to the Ordo Missae of 1969, the Roman Rite did not have such a congregational acclamation and the words Mysterium fidei were incorporated within the Words of Institution.