  While the term ‘moral naturalism’ has a number of different meanings, it is most frequently used to describe naturalistic versions of moral realism. Moral realists hold that there are objective, mind-independent facts and properties; moral naturalists hold that these objective, mind-independent moral facts are natural facts. ‘Moral naturalism’ can also be used as a label for views in normative ethics which hold that things are good if they are natural, or as a label for any view in metaethics which is consistent with a general metaphysical naturalism. But naturalistic moral realism is the subject of this entry. Moral naturalism appeals to many, since it combines the advantages of naturalism and realism, but others have argued that moral naturalism does inadequate justice to central dimensions of our practice with moral concepts. In this entry, we examine the most prominent arguments for and against moral naturalism, and profile three of the most popular and influential versions of moral naturalism.