Samuel J. Kerstein develops a new, broadly Kantian account of the ethical issues that arise when a person treats another merely as a means, that is, 'just uses' the other and thereby acts wrongly. He takes his inspiration from Immanuel Kant's 'Formula of Humanity', which commands that we treat persons never merely as means but always as ends in themselves. Kerstein questions the plausibility of an orthodox Kantian account of the dignity of persons before going onto develop a new, detailed account of his own, and then shows how the Kantian principles he develops shed light on pressing issues in bioethics. He investigates how, morally speaking, scarce resources such as flu vaccine ought to be distributed, explores the morality of regulated markets in organs,and contends that in many contexts, buying organs from live 'donors' fails to honour their dignity. How to Treat Persons champions the view that even if an agent gets another's voluntary, informed consent to use parts of his body for transplantation or medical research, she might nevertheless be treating him merely as a means or failing to respect his dignity.