A lawyer and literary critic, he was drawn into politics by the Dreyfus affair of 1894; he joined the Socialist Party in 1902 and became its leader in opposition in 1925. During the 1930s he led the Popular Front, being elected France’s first socialist and Jewish Prime Minister in 1936. He introduced significant labour reforms, but was forced to resign the following year. Interned in Germany during World War II, he returned to France to head a socialist caretaker Cabinet, and retained the party leadership until his death.