Aquinas sees the key elements of his ethics – happiness, law, virtue, and grace – as an interconnected whole. However, he seldom steps back to help his reader see how they actually fit together. In this book, Joseph Stenberg reconsiders the most fundamental ways in which Aquinas connects these major elements of his ethics. Stenberg presents a novel reading of Aquinas's account of individual happiness that is historically sound and philosophically interesting, according to which happiness is exclusively a matter of engaging in and enjoying genuinely good activities. He builds on that reading to offer an account of common happiness. He then shows that Aquinas defends a unique form of eudaimonism, Holistic Eudaimonism, which puts common happiness rather than individual happiness at the very heart of ethics, including at the heart of law, virtue, and grace. His book will appeal to anyone with an interest in Aquinas or the history of ethics.