Extended antipaternalism means the use of antipaternalist arguments to defend activities that harm (consenting) others. As an example, a smoker’s right to smoke is often invoked in defence of the activities of tobacco companies. It can, however, be shown that antipaternalism in the proper sense does not imply such extended antipaternalism. We may therefore approve of Mill’s antipaternalist principle (namely, that the only reason to interfere with someone’s behaviour is to protect others from harm) without accepting activities that harm (consenting) others. This has immediate consequences for the ethics of public health. An antipaternalist need not refrain from interfering with activities such as the marketing of tobacco or heroin, boxing promotion, driving with unbelted passengers, or buying sex from “voluntary” prostitutes.