Many contemporary legal positivists have argued that legal theory is evaluative because it requires the theorist to make judgments of importance. At the same time they argue that it is possible to know “what the law is” without resort to evaluative considerations. I distinguish between two senses of “what the law is”: in one sense it refers to legal validity, in another to the content of legal norms, and I argue that legal positivism is best understood (as indeed some legal positivists have explicitly said) as a claim about legal content. Understood this way, however, it is open to the objection that knowing the content of legal norms requires evaluative considerations for reasons similar to those offered by positivists for thinking that legal theory is requires evaluative considerations. I then distinguish between evaluative considerations in general and moral considerations and argue that because of the subject-matter of legal norms, there are good reasons for thinking that it is moral considerations, and not just any other evaluative considerations, that are required for knowing the content of legal norms.