Lady Bird (film)

Gerwig spent years writing the screenplay. At one point it was over 350 pages long, and had the working title Mothers and Daughters. In 2015, Gerwig and her team secured financing from IAC Films, who produced the film alongside Scott Rudin Productions. Gerwig's manager Evelyn O'Neill also served as a producer.

Question: was the movie lady bird based on a book
Answer: no