The term “Lost Generation” is believed to have been coined by Gertrude Stein; in early 20th-century Paris, she was a prominent writer, critic, and art collector. At her home, she hosted a salon attended by many famous writers and artists, including Hemingway. The Sun Also Rises popularized use of the term, in part, because in the epigraph Hemingway quotes Stein as saying: “You are all a lost generation.”

The Lost Generation, who came of age during World War I, were greatly affected by mechanized warfare and the way it led to mass death and destruction. In the years following the war, members of the Lost Generation are characterized as being aimless drifters who do not adhere to traditional forms of belief and structure.

Throughout the novel, the horrors of World War I linger in the background, contributing to the characters’ life philosophies—or lack thereof. In the war, millions were killed or wounded. Nationalistic fervor led to bloodshed. Traditional institutions either retreated or were used to further the destruction. Now, Jake and his companions have a hard time believing in anything. They wander drunkenly and often appear lost.