This important chapter focusses on the development and core characteristics of Augustine of Hippo’s views on justification, which were one of the most significant factors in shaping the western theological tradition’s reflections on this theme in the Middle Ages and during the Reformation debates of the sixteenth century. The chapter opens by considering the overall trajectory of Augustine’s views on grace, and how Paul’s concept of justification fits into this development. Augustine consistently interprets the Pauline concept of ‘justification’ to mean ‘a making righteous’, and does not develop a reputational or forensic approach to the concept. Augustine’s concept of the ‘righteousness of God is considered in some detail, with particular attention being paid to the manner in which Augustine distinguishes this theological use of the concept from its secular counterparts – as seen, for example, in the works of Cicero. The chapter also considers the ways in which Augustine’s approach to justification was affected by the Pelagian controversy, which tended to focus on the framework within which the concept of justification was set, rather than the notion of justification itself.