He was born in Toledo, Ohio, attended Oberlin College, did graduate work at Harvard University where he received a doctorate in 1952, as a student of Oscar Handlin.
He is best known for his 1971 book An Unsettled People: Order and Disorder in American Life. Berthoff was an Assistant Professor of History at Princeton University from 1953, and then a Professor of History at Washington University in Saint Louis, from 1962. He was made chairman of Washington University"s history department and named William Elliott Smith Professor of History in 1971.
He promoted social history and ethnic history.
His 1960 article on "The American Social Order: A Conservative Hypothesis," called for a conservative interpretation of American history.
Served to First lieutenant, infantry Army of the United States, 1942-1946. Member Southern History Association.
Married Tirzah Margaret Park, August 5, 1954. Children: Thomas Arthur, Margaret Olivia Berthoff-Fernandes, Andrew Warner, Clarissa Helen Joyce.