U.S. biographer whose clear writing was based on sound and thorough scholarship.

As an expatriate in Paris in the 1920s, Josephson was an associate editor of Broom (1922–24), which featured both American and European writers. He had believed that the American artist who wished to avoid being absorbed by industrialism had no choice but exile; soon, however, Josephson returned to America to watch what he described as the battle between mechanism and ideas. After coming close to a breakdown while working on Wall Street, he went back to writing and became an editor for the Paris-based magazine transition (1928–29).

His first book was a well-researched and authoritative biography of Emile Zola, Zola and His Time: The History of His Martial Career in Letters (1928). Other highly praised biographies followed. His interest in 19th-century French literature appears in such works as Victor Hugo (1942) and Stendhal (1946), which helped to regenerate American interest in Stendhal's work. He addressed another favourite topic, American economics, in what is perhaps his best known work, The Robber Barons: The Great American Capitalists, 1861–1901 (1934). The book chronicles the lives of John D. Rockefeller, Andrew Carnegie, and other barons of industry in the late 19th century. A late work is The Money Lords: The Great Finance Capitalists, 1925–1950 (1972).