The present volume is a part of the Corpus Troporum editions of liturgical tropes to the songs of the roman mass from the period from the tenth up to the twelfth century. It consists of three different parts: I. A critical edition of the texts of the Agnus Dei tropes. 2. An inventory of the entire repertories of Agnus Dei tropes with their localisation and rubrics and the structure of each single trope in the manuscripts used in the edition. 3. A historical background and a study of the form and the function of Agnus Dei tropes as reflected in the manuscripts.