The term "Celtic Rite" is applied to the various liturgical rites used in Celtic Christianity in Britain, Ireland and Brittany and the monasteries founded by St. Columbanus and Saint Catald in France, Germany, Switzerland, and Italy during the Early Middle Ages. The term is not meant to imply homogeneity; instead it is used to describe a diverse range of liturgical practices united by lineage and geography.

The Ambrosian Rite is a Latin liturgical rite of the Catholic Church. The rite is named after Saint Ambrose, a bishop of Milan in the fourth century. It is used by around five million Catholics in the greater part of the Archdiocese of Milan, in some parishes of the Diocese of Como, Bergamo, Novara, Lodi, and in the Diocese of Lugano, Canton of Ticino, Switzerland.