[The following is taken from St. Andrew Daily Missal, Dom Gaspar Lefebvre OSB, Copyright 1958, 1962 by Abbaye du St. Andre, Bruges, Belgium.]
The Practice of Dialogue Mass (sometimes called Missa dialogata or Missa recitata) is certainly one of the best ways of fostering participation at congregational Masses that are not sung. Not all the texts of the Mass should be said aloud by all the faithful: many belong to the priest alone (or to his assistants at solemn Mass): we can still make these parts our own, not by a mechanical repetition but by reverent and serious reflection, corresponding to the thoughts expressed by these prayers.
Other parts of the Mass were originally, and still are, meant to be said by the people. They are of two kinds: those that are to be chanted by the congregation at High Mass, and those that are answered by the ministers, or by the server at low Mass, on our behalf.
An instruction of the Congregation of Rites (de Musica sacra) issued Spetember 3, 1958, lays down four stages or degrees of dialogue Mass; by thus learning the practice gradually congregations can be brought to full participation in the holy mysteries.
The first stage is when the congregation makes the easier responses: Amen; Et cum spiritu tuo; Deo gratias; Gloria tibi, Domine; Laus tibi, Christe; Habemus ad Dominum; Dignum et iustum est; Sed libera nos a malo.
At the second stage the faithful say in addition all those parts which according to the rubrics should be said by the server. They also say before the Communion Domine, non sum dignus, three times.
At the third stage the faithful say with the priest those parts of the Ordinary of the Mass that at a high Mass are sung by the choir: the Kyrie, alternating the invocations, the Gloria in excelsis (joining with him from Et in terra pax), the Credo (from Patrem omnipotentem), the Sanctus and the Agnus Dei.
The fourth stage (which will be possible generally only in schools and other institutions and is allowed only on condition that it can be carried out with proper dignity) is when the congregation says with the priest certain parts of the Proper of the Mass: the Introit, the Gradual, the Offertory and the Communion.
Finally, continuing an innovation introduced by the recent reform in the liturgy of Good Friday, at low Masses the whole of the Pater noster may be recited in Latin by the faithful with the priest, all adding Amen at the end.
Assistance in this way at the holy Sacrifice is the ideal preparation for Holy Communion since it is that of the Pope, bishops and all priests, whenever they celebrate Mass. It develops in the soul those sentiments of contrition (from the Introit to the Collect), of faith (from the Collect to the Creed), of hope (at the Canon of the Mass), of love (at the Communion) and of gratitude (from the ablutions to the end), which are indispensable if the Eucharist is to be received fruitfully. By means of this preparation, the highest act of partcipation in the Mass is holy Communion. It obtains all its fruits, because it is one of the most perfect applications of the conditions required by the decree of St. Pius X, when he said, "a most abundant attainment of the effects of holy Communion is by a careful preparation and a thanksgiving proper to the reception of this divine Sacrament."