Lacouture, the esteemed French biographer of Nasser and Ho Chi Mint, has struck out with a home-grown leftist hero: in this long, reverential life, socialist leader Leon Blum, head of the 1936 Popular Front government, looks distinctly unimpressive. A Parisian intellectual of Jewish descent and aristocratic mien, Blum devoted much of his life to literary and dramatic criticism--from which Lacouture quotes extensively. His first political involvement centered around the Dreyfus case; next, he was shaken by the 1914 assassination of moderate socialist Jean Juares, and picked up Juares' mantle. Desirous (like Juares) of wedding patriotism and socialism, he joined the wartime cabinet as aide to a Socialist minister. After the war, he ran successfully for the National Assembly and tried unsuccessfully to keep the Socialist Party in one piece. It split in 1921, however, when the majority formed the new Communist Party, and Blum was left with the rump SFIO. To stress Blum's desire for unity, party factionalism is tediously detailed. Muting the turbulence of those years are long excerpts from Blum's speeches. Then, under economic and political duress, an election deal was struck between the Socialists, the Communists, and the Radical Party; and in 1936 Blum became prime minister. The government was a disaster: its chief domestic reform, the 40-hour week, was obtained amid increasing unemployment and fiscal crisis. And when Blum shilly-shallied on the Spanish Civil War, pleasing no one, the government fell. Lacouture tries to put all this--and Blum's wartime foundering--in the best possible light; but he is unconvincing. The standard Joel Colton biography makes a better, less effortful case for Blum's importance.