 This article does not try to untangle the relations between treating persons merely as means and these other concepts. It focuses on the notion(s), inspired by Kant and seemingly embraced in ordinary moral discourse, of treating persons, especially treating others, merely as means. In the idiom of the article, to say that someone is treating another as a means or, equivalently, using him, implies in itself no moral disapproval. To say that someone is treating a person merely as a means or, equivalently, just using him, suggests that she is using the other in a way subject to ethical criticism. The entry begins by focusing on the roots in Kant of discussion of treating persons merely as means. It then considers (morally neutral) notions of using another or treating him as a means, notions that are less straightforward than it might seem. The third section focuses on attempts to specify sufficient conditions for treating another merely as a means, some of which Kant himself suggests. According to Kant, to treat another merely as a means is to do something morally impermissible; it is to act wrongly. The next section examines challenges to this claim. Finally, the article considers accounts of when a person uses another, but not merely as a means.