Léon Blum (1872–1950) was many things: a socialist and political activist, leader of the Popular Front; a dedicated statesman who served as France's prime minister three times; a hero who courageously opposed anti-Semitism, Nazi aggression, and the pro-German Vichy government; a passionate lover of women, art, and life. A tireless champion for workers’ rights, Blum dramatically changed French society by establishing the forty-hour work week, paid holidays, and collective bargaining on wage claims. He was also a proud Jew and Zionist, and a survivor who endured the horrors of Buchenwald and Dachau. Unlike previous biographies that downplay the significance of Blum’s Jewish heritage on his progressive politics, Pierre Birnbaum’s portrait depicts an extraordinary man whose political convictions were shaped and driven by his religious and cultural background. The author powerfully demonstrates how Blum’s Jewishness was central to his milieu and mission from his earliest entry into the political arena in reaction to the Dreyfus Affair, and how it sustained and motivated him throughout the remainder of his life. Birnbaum’s Léon Blum is a critical chapter in the larger history of Jews in France.