Our ability to talk about God's action in the world is closely tied to our understanding of causality. With the advent of modern Newtonian science the conception of causality narrowed, and the discussion of divine action became locked into that contracted understanding. There seemed to be simply no room for God to act in the world without interfering with nature and the laws of science that describe it. Fortunately, the idea of causality has been greatly expanded through developments in contemporary science. Discoveries in quantum mechanics, cosmology, chaos theory, and biology have all led to a broader understanding of causality. These developments have opened two fundamentally new ways for theologians to ""unlock"" the discussion of divine action. One is to use the developments of science themselves to speak of God's action. The other is to speak of divine action not directly through the theories and interpretations of science, but rather through the broader understanding of causality that they suggest.,br> This book explores both approaches and argues that the latter provides a more effective way for discussing divine action. After showing that the idea of causality in contemporary science is remarkably reminiscent of key concepts in the philosophy of Thomas Aquinas, it then retrieves those notions and applies them to the discussion of divine action. In this way, it provides a sustained account of how the thought of Aquinas may be used in conjunction with contemporary science to deepen our understanding of divine action and address such issues as creation, providence, prayer, and miracles.