During the last few centuries, a practical dichotomy between God and humans has developed within moral theory. As a result, moral theory tends to focus only on humans where human autonomy is foundational or only on God where divine commands capriciously rule. However, the moral theology of Thomas Aquinas overcomes this dichotomy. For Thomas, humans reach their perfection by participating in God's wisdom and love. Perfecting Human Actions explores the ways humans participate in eternal law--God's wisdom that guides and moves all things to their proper action. The book begins with a thoughtful examination of the philosophic recovery of the notion of participation in Thomistic metaphysics. It then explains Thomas's theological understanding of the notion of participation to show how humans are related to God. It is discovered that when performing human actions, humans participate in the eternal law in two ways: as moved and governed by it, and cognitively. In reference to participation as moved and governed, humans are directed by God to their proper end of eternal happiness. This mode of participation can be increased by perfecting the natural inclinations through virtue, grace, and the gifts of the Holy Spirit. In reference to cognitive participation, humans as rational creatures can know their proper end and how to attain it. Through this knowledge of moral truths, the intellect participates in the eternal law. Cognitive participation is perfected by the intellectual virtues (especially faith) and the gifts of the Holy Spirit (especially wisdom). The book concludes by showing how the notion of human participation in the eternal law is a much better foundation for moral theory than the contemporary notion of autonomy.