Bab's Diary is a 1917 American silent romantic comedy film directed by J. Searle Dawley and starring Marguerite Clark.

The film's scenario was written by Martha D. Foster, based on the screen story "Her Diary" by Mary Roberts Rinehart.

As described in a film magazine,[2] Barbara Archibald (Clark), nicknamed Bab, objects to being pushed into the background and, to give her family something to think about, declares that she is in love and is about to be married and end it all.

He also volunteers to personally deliver an impassioned love note she penned to her imaginary sweetheart by the name she had selected for him.

An actor made up like the photograph is introduced to Bab and persists in his attentions until she flees from the house.