is a children's novel by British writer Penelope Farmer. It is the story of Charlotte, a young girl sent to a boarding school where she begins travelling back in time every other night, switching places with a girl called Clare. Alternating between 1963 and 1918, the book takes a frightening turn when the girls find themselves stuck in the wrong decades.
Notable for its philosophical themes and questions of identity and self, the book inspired Robert Smith of The Cure
to write the song Charlotte Sometimes