Utilitarianism is a classic work of ethical theory, arguably the most persuasive and comprehensible presentation of this widely influential position. While he didn't invent utilitarianism, John Stuart Mill offered its clearest expression and strongest defense, and he expanded the theory to account for the variety in quality that we find among pleasures and pains. The complete text of the 1871 edition is included, along with selections from Jeremy Bentham's An Introduction to the Principles of Morals and Legislation. Andrew Bailey's detailed introduction examines the context of Mill's writing and offers guidelines on how to read the text accurately and critically.