Knowles was born in Fairmont, West Virginia, the son of James M. Knowles, a purchasing agent from Lowell, Massachusetts, and Mary Beatrice Shea Knowles from Concord, New Hampshire. His father was vice president of a coal company, earning an income which afforded them a comfortable living.
Knowles attended St. Peter's High School in Fairmont, West Virginia from 1938 until 1940, before continuing at Phillips Exeter Academy in Exeter, New Hampshire, graduating in 1942. Knowles graduated from Yale University as a member of the class of 1949.
He died in 2001 at the age of 75. Following his time at Phillips Exeter, Knowles spent two years serving in the U.S. Army Air Forces in World War II. While at Yale, Knowles contributed stories to campus humor magazine The Yale Record and served on the board of the Yale Daily News during his sophomore, junior and senior years, notably as editorial secretary during his senior year. He was a record-holding varsity swimmer during his sophomore year.
Early in Knowles's career, he wrote for the Hartford Courant and was assistant editor for Holiday magazine. With encouragement from Thornton Wilder, he concurrently began writing novels. Was first published in London by Secker and Warburg in 1959.
Published in New York in 1960 by Macmillan, it would be his most celebrated work. The novel is based upon Knowles's experiences at Phillips Exeter Academy. The setting of "The Devon School" is a thinly veiled fictionalization of it, with both campus and town easily recognizable.
Although the plot is not autobiographical, elements of the novel stem from personal experience, including Knowles' membership in a secret society, and sustaining of a foot injury while jumping from a tree during society exercises. In his essay, "A Special Time, A Special Place," Knowles wrote:The only elements in which were not in that summer were anger, violence, and hatred. There was only friendship, athleticism, and loyalty.
The secondary character Finny (Phineas) is the best friend of the main character Gene. Knowles has stated that he modeled Finny on David Hackett from Milton Academy, whom he met when both attended a summer session at Phillips Exeter Academy. A student called Phineas Sprague lived in the same dormitory as Knowles during the summer session of 1943 and may have inspired the character's name.
In his memoir Palimpsest, Gore Vidal acknowledges that he and Knowles concurrently attended Phillips Exeter Academy, with Vidal two years ahead. Vidal states that Knowles told him that the character Brinker is based on Vidal. "We have been friends for many years now," Vidal said, "and I admire the novel that he based on our school days, ".
"We have been friends for many years now,".