This Element critically surveys the full range of G. E. Moore’s ethical thought, including: (1) his rejection of naturalism in favor of the view that ‘good’ designates a simple, indefinable property, which cannot be identified with or reduced to any other property; (2) his understanding of intrinsic value, his doctrine of organic wholes, his repudiation of hedonism, and his substantive account of the most important goods and evils; and (3) his critique of egoism and subjectivism and his elaboration of a non-hedonistic variant of utilitarianism that, among other things, creatively blends aspects of act- and rule-oriented versions of that theory.