The relation between divine grace and human free will was one of the vehemently debated issues in the Pelagian controversy. In the current article we study how Pelagius, Jerome and Augustine understood the impact of divine grace on the three interrelated aspects of every human act, i. e. human ability (posse), willing (uelle), and being (esse). We start with an analysis of the doctrine of grace Pelagius developed in (the preserved) fragments of his treatise Pro libero arbitrio and in his previous literary production. Next, we indicate the (differing) ways in which Jerome and Augustine read, (mis)represented, and severely criticized Pelagius’ view on the interaction between God’s grace and mankind’s posse, uelle, and esse. Finally, we will d...