Whether Maximus the Confessor knew of Augustine is a question of long standing uncertainty. In this paper, new evidence in the matter is presented through Maximus’ knowledge of the acta of the Lateran Council of 649. His later use of the acta reveals that he considered Augustine as one of the fathers of the Church whose teaching disproved monothelitism. In addition, following Rudolf Riedinger’s plausible thesis that Maximus is the author of the Lateran acta, a significant connection occurs through the acta’s use of two Augustinian texts from the fifth book of Contra Julianum opus imperfectum. These are woven into the argument in one of the acta’s final speeches, attributed to Maximus of Aquileia. The way these texts are cited and commented on clearly discloses the author’s familiarity with the extended context of the passages. This paper investigates the reason why this Augustinian work was particularly helpful in refuting one of the core ideas of monothelitism—the idea that everything natural is forced by necessity and that the will, if natural, consequently would lack genuine volition—an idea that was also held by Julian of Aeclanum. The paper also demonstrates Maximus the Confessor’s use of the structure of Augustine’s argument at other occasions and presents an argument for Maximus’ authorship of Maximus of Aquileia’s speech.