Ethical naturalism is an ethical theory that holds that practical norms are a species of natural norms. It was a position held by almost all ancient ethical theorists, but despite a renaissance among some in the past three quarters of a century, it fell by and large into ill repute centuries ago. This dissertation aims to assess contemporary naturalism in light of that history. In chapter two, I note that contemporary ethical naturalism has had little interest in the historical background of their own theorizing, and I try to fill that gap. The remaining chapters contribute to this task. In chapter three, I explore the concepts of nature at work in some of the writings of Aristotle and Cicero, suggesting that Aristotle has a richer conceptu...