Since its first publication in 1859, few works of political philosophy have provoked such continuous controversy as John Stuart Mill\'s On Liberty, a passionate argument on behalf of freedom of self-expression. This classic work is now available in a new edition that also includes essays by distinguished scholars in a range of fields. The book begins with a biographical essay by David Bromwich and an interpretative essay by George Kateb. Then Jean Bethke Elshtain, Owen Fiss, Judge Richard A. Posner, and Jeremy Waldron present commentaries on the pertinence of Mill\'s thinking to current debates. They discuss, for example, the uses of authority and tradition, the shifting legal boundaries of free speech and free action, the relation of personal liberty to market individualism, and the tension between the right to live as one pleases and the right to criticize anyone\'s way of life.