Lisa and Lottie, or The Parent Trap is a 1949 German children's novel by Erich Kästner. The book is about identical twin girls whose parents separated them in infancy upon divorcing, only to reunite at a summer camp years later before switching places.

Emil Erich Kästner was a German writer, poet, screenwriter and satirist, known primarily for his humorous, socially astute poems and for children's books including Emil and the Detectives and The Parent Trap. He received the international Hans Christian Andersen Medal in 1960 for his autobiography Als ich ein kleiner Junge war. He was nominated for the Nobel Prize in Literature in six separate years.