This study of the Lord’s Supper (which Barth did not live to write) systematically develops the implications of Karl Barth’s doctrine of God for his view of the sacrament. It analyzes his conceptions of God, revelation, grace, and sacramental causality, critically comparing them to the views of Rahner, Torrance, Wainwright, Juengel, Moltmann, Pannenberg, Gunton, and others. By contrasting Barth’s views with more recent theology, this study clarifies many important issues that are often neglected or misunderstood by theologians who have moved beyond Barth without grappling with the important questions he raised, especially concerning God’s freedom. Sacramental controversies are explored in the context of Christology and Trinitarian theology.