Knoles taught American social and intellectual history at Stanford from 1935 until his retirement in 1972 and served as chairman of the History Department his last 10 years. He was the Margaret Byrne Professor of American History, Emeritus.
Knoles was involved with the Stanford Historical Society, and donated his papers to the Stanford University Libraries' Department of Special Collections and University Archives.
Knoles was born on Feb. 20, 1907, in Los Angeles, one of eight children. When he was 13, the family moved to San Jose, where his father became president of the University of the Pacific, now in Stockton.