The Trinitarian Christology of St Thomas Aquinas brings to light the Trinitarian riches in Thomas Aquinas’s Christology. Dominic Legge, O.P, disproves Karl Rahner’s assertion that Aquinas divorces the study of Christ from the Trinity, by offering a stimulating re-reading of Aquinas on his own terms, as a profound theologian of the Trinitarian mystery of God as manifested in and through Christ. Legge highlights that, for Aquinas, Christology is intrinsically Trinitarian, in its origin and its principles, its structure, and its role in the dispensation of salvation. He investigates the Trinitarian shape of the incarnation itself: the visible mission of the Son, sent by the Father, implicating the invisible mission of the Holy Spirit to his assumed human nature. For Aquinas, Christ’s humanity, at its deepest foundations, incarnates the very personal being of the divine Son and Word of the Father, and hence every action of Christ reveals the Father, is from the Father, and leads back to the Father. This study also uncovers a remarkable Spirit Christology in Aquinas: Christ as man stands in need of the Spirit’s anointing to carry out his saving work; his supernatural human knowledge is dependent on the Spirit’s gift; and it is the Spirit who moves and guides him in every action, from Nazareth to Golgotha.