Utilitarianism, the approach to ethics based on the maximization of overall well-being, continues to have great traction in moral philosophy and political thought. This Companion offers a systematic exploration of its history, themes, and applications. First, it traces the origins and development of utilitarianism via the work of Jeremy Bentham, John Stuart Mill, Henry Sidgwick, and others. The volume then explores issues in the formulation of utilitarianism, including act versus rule utilitarianism, actual versus expected consequences, and objective versus subjective theories of well-being. Next, utilitarianism is positioned in relation to Kantianism and virtue ethics, and the possibility of conflict between utilitarianism and fairness is considered. Finally, the volume explores the modern relevance of utilitarianism by considering its practical implications for contemporary controversies such as military conflict and global warming. The volume will be an important resource for all those studying moral philosophy, political philosophy, political theory, and history of ideas.