Franklin D. Roosevelt was president during two of the most serious crises of the twentieth century—the Great Depression (1929-41) and World War II (1939-45). During both ordeals, he was able to make ready massive efforts and rally tremendous support from government and the American people. He was the only president elected more than twice, and he won each of his four presidential elections by wide margins.

Roosevelt was skilled at building coalitions (alliances of support), often among diverse political groups. He favored frequent experimentation and change when progress stalled. His social programs, called the New Deal, offered relief and jobs to struggling Americans during the Depression. The New Deal also reformed financial practices that had contributed to the Depression. Roosevelt's administration instituted such acts as the Social Security program, which guarantees financial support to Americans upon retirement.

The Depression ended as the...