No president looms larger in twentieth-century American history than Franklin Delano Roosevelt, and few life stories can match his for sheer drama. Following in the footsteps of his Republican cousin President Theodore Roosevelt, FDR devoted himself to politics as a Democrat and a true man of the people. Eventually setting his sights on the presidency, he was elected to office in 1932 by a nation that was mired in the Great Depression and desperate for revival.

As the distinguished historian Alonzo Hamby argues in this authoritative biography, FDR's record as president was more mixed than...