The White House said the store, One More Page Books, is an "independent, neighborhood bookstore."
The president -- accompanied by his daughters Sasha and Malia -- used his BlackBerry, evidently to look up a book title, as he conversed with Eileen McGervey.
"Preparation," he said. "That's how I shop."
When a reporter covering the visit asked Obama a question about the upcoming fiscal cliff, the president said: "We're doing Christmas shopping. Happy Thanksgiving, folks."
Obama and his daughters spent a few minutes walking through the store, where he shook hands with several employees.
The White House said the president bought 15 children's books to be given as family Christmas gifts, but did not release a list of titles.