The film was Universal Pictures' first European production. Julie Christie was originally cast as just Linda Montag, not both Linda and Clarisse. The part of Clarisse was offered to Jean Seberg and Jane Fonda. Tippi Hedren was also considered, but Hitchcock told Truffaut that she was not available. After much thought, Truffaut decided that the characters should not have a villain/hero relationship but rather be two sides of the same coin and cast Christie in both roles, although the idea came from the producer, Lewis M. Allen.