This is the fourth edition (2022) of the “Red Code”; it is edited by Juan Ignacio Arrieta, originally edited by Prof. E. Caparros in 2003, and based on the commentaries elaborated by the Martin de Azpilcueta Institute. It provides a thorough, practical understanding of the laws of the Church through 1876 pages of legal texts and commentaries on the canons. This fourth edition includes texts and commentaries on the newly revised Book VI of the Code of Canon Law, which substantially modifies penal discipline. Internal references to penal canons throughout the book have likewise been updated. Also impelling revisions in this fourth edition are recently modified texts related to disciplinary matters, theological understandings, perspectives on ecclesiastical institutions, functions of disciplinary procedures, and others.