This essay argues the image of the ‘Mystical Body’ or ‘Body of Christ’ is fully intelligible only in light of the Cross. The Body of Christ is a cruciform Body. As the Body of Christ crucified and risen, it is presently being configured to Christ in the world through self-sacrificial love. The essay traces the place of the Cross in some representative twentieth-century Catholic theologies of the Mystical Body, in light of the perspective of Thomas Aquinas. I first survey four theologians from the first half of the century who, in their understandings of the Mystical Body, gave a place to the Cross: Emile Mersch, Fulton Sheen, Charles Journet, and Pius Pasch. Here I also examine Pope Pius XII's encyclical Mystici Corporis. Second, I explore the approach of some notable Thomistic theologians or interpreters of Aquinas from the early 1960s onward: Jerome Hamer, M. J. Le Guillou, George Sabra, Jean-Pierre Torrell, and Herwi Rikhof. In this section, I also examine Vatican II's Lumen Gentium. My third and final section treats Aquinas himself, in order to reflect upon the place of the Cross in his understanding of the Mystical Body, as found in his biblical commentaries and the Summa theologiae.