Signs of its success were visible almost immediately after it was published in July 1960. Both Book-of-the-Month Club and the Literary Guild made the novel one of their selections, and Reader’s Digest condensed it. A week after publication, the novel jumped to the top of the best-seller lists; it remained there for 88 weeks.

Life magazine accompanied Ms. Lee around Monroeville, photographing her with her father on the front porch of the family home, posing on the balcony of the country courthouse and peering in the window of the ramshackle house that served as the model for the home of Boo Radley, the gentle, simpleminded neighbor who befriends Scout. One photograph bore the retrospectively poignant caption: “At her father’s law office where she wrote ‘Mockingbird,’ Miss Lee works on her next novel.”

The next novel refused to come. “Success has had a very bad effect on me,” Ms. Lee told The Associated Press. “I’ve gotten fat — but extremely uncomplacent. I’m running just as scared as before.”

In the months after the novel was published, she contributed two wispy articles to McCall’s and Vogue. To inquiring reporters, she threw out tantalizing hints of a second novel in progress, but the months and the years went by, and nothing appeared in print. She began turning down requests for interviews.

In one of her last interviews, with a Chicago radio show in 1964, Ms. Lee talked in some detail about her literary ambition: to describe, in a series of novels, the world she grew up in and now saw disappearing.

“This is small-town middle-class Southern life as opposed to the Gothic, as opposed to ‘Tobacco Road,’ as opposed to plantation life,” she told her interviewer, referring to the Erskine Caldwell novel, and adding that she was fascinated by the “rich social pattern” in such places. “I would simply like to put down all I know about this because I believe that there is something universal in this little world, something decent to be said for it, and something to lament in its passing,” she continued. “In other words, all I want to be is the Jane Austen of South Alabama.”

The world waited impatiently, and grew accustomed to disappointment. At one point her sister told a British journalist that the nearly completed manuscript had been stolen from Ms. Lee’s apartment during a break-in. In the mid-1980s Ms. Lee became fascinated by a part-time preacher and serial killer whose story she intended to dramatize, after the manner of “In Cold Blood,” in a book tentatively titled “The Reverend.” She even set up camp for nearly a year in Alexander City, Ala., the site of the killings, to do research and absorb the atmosphere. But again nothing materialized.