The automatic book-end system for shelves includes a shelf, a book-end housing that is movably connected to the shelf, and a limit switch connected to the book-end housing. The housing includes a rechargeable battery, an electric circuit, electric motors, and a pair of chain sprockets. The shelf includes a pair of roller chains that engage the chain sprockets. The electric motors, chain sprockets, and roller chains work in conjunction to achieve linear motion of the housing along the shelf bottom. The book-end housing can support the books in an upright, side by side arrangement on the shelf. Once a book is removed from the shelf, the housing is automatically repositioned to push the remaining books together and close any resulting gaps between the remaining books.