Moral dilemmas set a challenge for ethical theory. They are situations where agents seem to be under an obligation both to do, and to refrain from doing, a specific act. Are such situations possible? What is their exact nature? These are the questions that Moral Dilemmas tries to answer. The book argues that moral theories should not allow for the possibility of irresolvable dilemmas, for situations in which no right answer exists. To this end, arguments seeking to prove the existence of irresolvable dilemmas, especially the argument from the incommensurability of values, are discussed at length and refuted. The book shows that though on the normative level dilemmas are resolved, they typically involve a high moral cost for which there is no adequate compensation. This moral cost is the source of the regret and pain suffered by agents in moral dilemmas. Thus, moral dilemmas do not point to any inconsistency in our moral reasoning or theory, but to a problematic aspect of the human condition; at times (probably less often than is usually believed), human beings are justified, and even required, to dirty their hands by behaving in ways that in ordinary situations would be strictly forbidden and condemned.