Claire Danes, Eddie Marsan, Leo Bill and Imogen Poots have joined the cast of the film adaptation of the Robert Kaplow book.
Zac Efron and Ben Chaplin will also star in the film, which takes place in 1937 when a student (Efron) is spotted by Welles in the streets of New York. When Welles, the founder of the Mercury Theater, casts the boy in his production of Julius Caesar, he is thrust into the limelight.
Christian McKay will play Orson Welles, while Ben Chaplin will play English actor George Coulouris.
The screenplay was written by Vince Palmo and Holly Gent Palmo, who also worked with Linklater for the comedy Dazed and Confused.
Filming begins in February in London and New York.