Sophie's World is a 1991 novel by Norwegian writer Jostein Gaarder. It follows Sophie Amundsen, a Norwegian teenager, who is introduced to the history of philosophy as she is asked "Who are you?" in a letter from an unknown philosopher. The nonfictional content of the book aligns with Bertrand Russell's The History of Western Philosophy.

Jostein Gaarder is a Norwegian intellectual and author of several novels, short stories, and children's books. Gaarder often writes from the perspective of children, exploring their sense of wonder about the world. He often utilizes metafiction in his works and constructs stories within stories. His best known work is the novel Sophie's World: A Novel About the History of Philosophy (1991). It has been translated into 60 languages; there are over 40 million copies in print.