This book explores the political and personal life of an extraordinary woman. Opposed to both authoritarianism and instrumental reformism, an advocate of radical democracy and individual responsibility, Rosa Luxemburg (1871-1919) is perhaps the most eminent representative of the libertarian socialist tradition, and her work still sparks political and scholarly debate. This volume offers the most extensive collection of Rosa Luxemburg's letters available in English. This new edition adds a wealth of new material, including nearly fifty new letters which have never before been published in English. This remains an essential work for examining the tradition of libertarian socialism and its unfulfilled democratic promise.