One Battle After Another was based on Thomas Pynchon's novel Vineland, according to its Adapted Screenplay Oscar listing. Paul Thomas Anderson wrote the screenplay and received the Academy Award for Best Adapted Screenplay at the 98th Oscars.
Vineland was published in 1990 and is set largely in California, combining political satire, counterculture, family drama, and Pynchon's distinctive interest in conspiracy and state power. Anderson had considered adapting the novel for years before developing the film's eventual story.
The movie is not a scene-by-scene translation of the book. It is a loose adaptation inspired by Vineland's themes, political atmosphere, and father-daughter dynamic, while also incorporating ideas from other story concepts Anderson had developed. The film changes characters, chronology, setting details, and plot structure.
That looseness can cause confusion with Inherent Vice, another Pynchon adaptation directed by Anderson. Inherent Vice was directly adapted from Pynchon's 2009 novel of the same name; One Battle After Another instead drew its source inspiration from Vineland.