Many philosophers insist that moral facts or properties play no role in explaining (non-normative) natural phenomena. The problem of moral explanation has raised metaphysical, semantic and epistemic challenges to contemporary moral realism. In my dissertation, I attempt to vindicate the explanatory efficacy of moral properties, while at the same time respecting the autonomy and normativity of morality. In doing so, I will advocate a sort of non-reductive ethical naturalism, according to which moral properties are natural properties (in the sense that they are open to empirical investigation), and yet remain irreducible to non-normative natural properties, such as psychological, biological, and sociological properties. More specifically, I...