This book discusses the Kyrie eleison in the three Latin Rites, namely, Roman, Ambrosian and Hispano-Mozarabic Rites. It presents the real theological meaning and liturgical function of the Kyrie eleison in the Post-Conciliar Mass and the Liturgy of the Hours. It also presents the liturgical use and theological significance of the elements before the Kyrie eleison prior to the Kyrie eleison in the Order of the Mass.