In 1958, Juster had received a Ford Foundation grant for a children's book about cities. Unable to make progress on that project, he turned to writing what became "The Phantom Tollbooth", his first book. His housemate, Feiffer, a cartoonist, interested himself in the project. Jason Epstein, an editor at Random House, bought the book and published it. The book received rave reviews and has sold in excess of three million copies, far more than expected. It has been adapted into a film, opera, and play, and translated into many languages.