The object of this paper is to review and examine some of the things which G. E. Moore says about the nature of intrinsic value, about the sort of objects which possess it, and about the method of ascertaining the intrinsic values of things. Most of the discussion will be based on Principia Ethica (1903): for in that work Moore stated the substance of his ethical theories once and for all. He explicitly changed his mind later on a few specific issues, which will be noted when they arerelevant: and I shall argue in my fourth section that he also changed his mind in one matter without acknowledging that he was doing so. With those exceptions, it seems to me that his later writings differ from Principia chiefly by their style of presentation and by the introduction of some new distinctions, and I shall think myself justified, on most points, in treating them as an aid to amplifying or refining the position which Moore adopted in Principia.The other works to be referred to are Ethics (1912); “The conception of intrinsic value”, written about 40 years ago and published in Philosophical Studies; “Is goodness a quality?” in Arist. Soc. Sup. Vol. 1932; and “A reply to my critics” in The Philosophy of G. E. Moore, edited by Schilpp (1942). The last work will be cited as Reply.