The distinction between killing and letting die is too simple. A third category – preventing people from being saved – must also be recognized. Like killing, preventing a person from being saved is a species of doing harm; like killing, it infringes one of the victim's negative rights. Yet preventing a person from being saved is morally on a par with letting die, which infringes one of the victim's positive rights. It follows that we cannot explain the moral inequivalence of killing and letting die by saying, as so many have, that negative rights are more stringent than positive rights. A more promising strategy is suggested at the end of the article.