Faction.

One of the most-discussed books of the 1960s was Truman Capote's In Cold Blood (1966). Variously promoted as a "nonfiction novel" and as "faction," the book was based on actual murders in Kansas on 15 November 1959, the trial in May 1960, and the hanging of the murderers in April 1965. Capote, already a well-known novelist, interviewed people in Kansas and wrote about the story in the form of a novel. Sales of the book skyrocketed, and Capote, no resister of publicity, basked in the limelight. Scores of imitations followed, with varying success. The most notable example, Norman Mailer's The Armies of the Night: History as a Novel, the Novel as History (1968), was about his participation in an October 1967 peace march on the Pentagon and includes Mailer as a character.

The New Journalism.

Almost as popular were books with firmer roots in journalism—or the New Journalism, to be precise. The...