From his engagement with Pelagius to his late writings to the monks of Gaul, Augustine repeatedly invoked Ambrose’s Commentary on Luke to support his “anti-Pelagian” cause. In his struggle against Pelagius, he calls attention to how Ambrose, using one of Augustine’s favorite “anti-Pelagian” proof texts, Proverbs 8:35 (“the will of human beings is prepared by God”), presents God’s grace as the basis for conversion (nat. et grat. 63.75). In another work against the namesake of the Pelagian controversy, Augustine cites the same commentary to prove Ambrose’s support for the ideas that God cooperates with our wills, that God helps our wills in Christ, and that God calls and makes religious whomever he wills (grat. et pecc. or. 1.44.48-1.50.55). A decade later, Augustine again alludes to Ambrose’s commentary to drive home the second and third of these points, this time in the context of his efforts to respond to monks in Gaul disturbed by his teaching on grace and to counter Julian of Eclanum (perseu. 19.49; c. Iul. imp. 1.93). This paper will analyze these appeals to Ambrose’s Commentary on Luke, together with Augustine’s use of a key passage from Ambrose’s Flight from the World that may have played an important role in leading Augustine to the notion of a distinct human will in Christ, as potential indications of Ambrose’s role in shaping Augustine’s thinking on the human will more broadly speaking, an aspect of Augustinian thought often regarded as innovative both within and without the Christian tradition.