What Maisie Knew is an 1897 novel by American/British author Henry James. The story was first published in The Chap-Book and the New Review, two prominent American literary magazines of the time.
The protagonist of the book is Maisie, a young girl whose parents are divorced. The book follows her growth and development over the course of many years, as she evolves from a little girl to a more mature, sensible adolescent. Maisie has a difficult upbringing, as the book chronicles, for her parents use her as a tool to exact revenge on each other and to vent their frustrations from a bad divorce. Eventually, her parents abandon her entirely, and Maisie must make a tough choice about which of the guardians in her life she wants to care for her.
What Maisie Knew is an extremely influential piece of American literature, analyzed by many scholars and critics over the years. Maisie's psychological growth has been a prominent subject of study; a few scholars point to her as a paradigm of Freudian developmental psychology. The book was also adapted into a successful movie in 2012.