Diary of a Lost Girl is a 1929 German silent film directed by G. W. Pabst and starring American silent star Louise Brooks. The film was shot in black and white, and diverse versions of the film ranged from 79 minutes to 116 minutes in length. This was Brooks' second and last film with Pabst, and like their previous collaboration, Pandora's Box, many film historians consider it to be a classic. It is based on the controversial and bestselling 1905 novel of the same name by Margarete Böhme. The novel had been previously adapted by Richard Oswald as Diary of a Lost Woman.