Diary of a Lost Girl (German: Tagebuch einer Verlorenen) is a 1929 German silent film directed by G. W. Pabst and starring American silent star Louise Brooks. The film is shot in black and white, and diverse versions of the film range 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.