Singing the Mass starts with singing the dialogues and responses and the Pater Noster (first degree of participation per Musicam Sacram paragraph 28), then singing the Kyriale and Credo (second degree).
Wikipedia defines the “Kyriale” as a “collection of Gregorian Chant settings for the Ordinary of the Mass”. In the context of singing at Mass, the words “Kyriale”, “Ordinary” or “Mass settings” mean basically the same thing. But “Kyriale” emphasizes the 1500-year tradition. Those who sang some of the eighteen Gregorian Masses and six Credos also know that it is one of the richest and most beautiful musical traditions of the Church. “Tradition” implies that this “Kyriale” was handed over to us over the centuries. Over hundreds and hundreds of years, the clergy, musicians and faithful who knew their “Kyriale” gave their time to pass along their skills. Centuries after centuries, they would teach their congregations and foster the “active participation” that Vatican II reminds us is always a priority in the Catholic Liturgy. We propose to continue this tradition.
You can practice four different Kyriale on this site: