This text defends moral cognitivism with a new approach. The author maintains that the truth of moral judgments is determined in fundamentally the same way as is the truth of non-moral judgments, in other words by appeal to truth conditions which are incorporated in beliefs held in common by a wide variety of societies. She argues that if a moral theory can be developed which can account for widely held, well-established moral beliefs, this would provide a set of truth conditions for moral judgments. A theory designed to do this - and through which major moral disagreements can be resolved - is presented here, together with discussions of many actual and possible objections. The book is intended for professional philosophers and advanced students of philosophy.