Paul Levi remains one of the most interesting and controversial figures in the early history of the Communist movement. As leader of the KPD after the murder of Rosa Luxemburg and Karl Liebknecht, he successfully built up a party of a third of a million members, but by 1921 Comintern pressure for ‘Bolshevisation’ forced Levi’s resignation and expulsion. Until his early death in 1930 he remained ‘a revolutionary socialist of the Rosa Luxemburg school’ (Carl von Ossietsky), and was described by Albert Einstein as ‘one of the wisest, most just and courageous persons I have come across’. The first English edition of Levi’s writings fills a long-standing gap in the documents of German Communism.