John Stuart Mill (1806–73) ranks among the very greatest thinkers of the nineteenth century. His impact through his books, journalism, correspondence, and political activity on modern culture and thought has been immense, and his continuing importance for contemporary philosophy and social thought is widely recognised. This Companion furnishes the reader with a systematic and fully up-to-date account of the many facets of Mill's thought and influence. New readers will find this the most convenient and accessible guide to Mill currently available. Advanced students and specialists will find a conspectus of recent developments in the interpretation of Mill.