This book presents the canonical institutions principally potestas regiminis and ecclesiastical offices which are the backbone of the entire governance structures within the Catholic Church from the Roman Pontiff to the parish priest It offers a canonical treatment of the material which at the same time refers to the underlying theological principles It is as well a reflexion on the pastoral form of exercising governance for the good of souls Juan Ignacio Arrieta full professor at the Faculty of Canon Law of the Pontifical University of the Holy Cross has served as Dean of this Faculty from 1984 to 1998 He is the editor of the journal Ius Ecclesiae He is also Consultor for the Pontifical Councils for the Interpretation of Legislative Texts and for the Family as well as Referendarius at the Supreme Tribunal of the Apostolic Signatura He holds Doctorates in Civil Law and in Canon Law from the University of Navarra Father Arrieta coedited with Professor Pedro Lombardia t