What Maisie Knew is a 2012 drama film directed by Scott McGehee and David Siegel and written by Carroll Cartwright and Nancy Doyne. Starring Julianne Moore, Alexander Skarsgård, Onata Aprile, Joanna Vanderham and Steve Coogan, it is a modern adaptation of Henry James' 1897 novel What Maisie Knew. The film finds six-year-old Maisie in the middle of a custody battle between her neglectful parents and their new partners.

Cartwright and Doyne wrote the film's script in 1995 but the project languished in development hell until McGehee and Siegel were hired as directors. It was filmed in New York over seven weeks in 2011 with music scored by DeVotchKa's Nick Urata. The film premiered at the 2012 Toronto International Film Festival, and was theatrically released on May 3, 2013, by Millennium Entertainment. It earned $2.7 million at the global box office and received positive reviews from critics.