The original working title of To Kill a Mockingbird was Atticus. Harper Lee’s manuscript developed from an earlier draft titled Go Set a Watchman, which was set around an adult Scout returning to Maycomb.
As Lee revised the manuscript with editor Tay Hohoff, the story shifted toward Scout’s childhood and the events surrounding Tom Robinson’s trial. During that process, the book was temporarily titled Atticus, reflecting the central role of Scout’s father and his moral position in the novel.
Lee eventually rejected that title because the story was not simply a portrait of Atticus Finch. It also explored Scout and Jem’s childhood, Boo Radley, Maycomb society, racial injustice, class prejudice, and moral growth. The final title, To Kill a Mockingbird, captured the novel’s broader themes through its symbol of innocence harmed by cruelty.
A common mix-up is treating Go Set a Watchman as merely an alternate title. It was an earlier draft that was later substantially transformed into the 1960 novel.