The concept of well-being plays a central role in moral and political theory. Policies and actions are justified or criticized on the grounds that they make people better or worse off. But is there really such a thing as well-being, and if so, what is it? Is it pleasure, desire-satisfaction, knowledge, virtue, achievement, some combination of these, or something else entirely? How can we measure well-being, amongst individuals and society? And how can we use it to make moral judgements about people, policies and institutions? In this entertaining and accessible new book, Ben Bradley guides readers through the various philosophical theories of well-being, such as hedonism, perfectionism and pluralism, showing the benefits and drawbacks of each theory. He explores the role of well-being in moral and political theory, and the limitations of welfare-based approaches to ethics such as utilitarianism and welfare egalitarianism. Finally, he introduces puzzles about well-being that arise in moral and prudential deliberations about procreation and death. Well-Being is an ideal introduction to these topics for those with no philosophical background, or for philosophers looking for an overview of current thinking about the subject.