Ethical non-naturalism, as I shall understand it, is the view that there are real ethical properties and facts that are not among the natural properties and facts of the world. This is to say that ethical properties (such as moral Tightness or goodness) and facts (such as the fact that an act is wrong, or that a certain consideration is a reason for acting) are neither among the properties and facts that are the proper subject of scientific inquiry, nor constructible from those that are. They are instead sui generis. Ethical non-naturalists are thus ethical realists who reject naturalistic construals of ethical properties and facts.