There is overwhelming consensus today that passively allowing someone to die in medical contexts is sometimes morally permissible and desirable. Active euthanasia, however, remains controversial. The legal systems and the medical establishments of both the United States and Canada maintain absolute, formal prohibitions against direct killing in medical settings. This clearly reflects the deep-seated belief, evident throughout our cultural and religious history, that there is some important moral difference between killing and allowing to die. Yet much that has been written recently on this topic by philosophers has denied moral relevance for this distinction. While this general conclusion appears to have gained popularity, especially within philosophy, the reasons advanced for it seem inconclusive to some. In what follows I examine the principal philosophical argument for the claim of irrelevance. I then develop an alternative view that, to my knowledge, has not been distinctly articulated in the current literature. I begin, however, with a preliminary discussion of the intuitive basis of the distinction between killing and letting die.