Ian and Betty Ballantine were book publishers who contributed to the growth of paperback book sales in the United States between the 1940s and the 1990s. The Ian and Betty Ballantine Books and Business Records include the Ballantines' materials related to Penguin Books USA, Bantam Books, Ballantine Books, and Peacock Books. Administrative documents cover the management of these presses as well as the editorial, sales, inventorying, and advertising processes. In addition, the collection contains the bulk of the editorial libraries of Penguin Books USA, Bantam Books, and Ballantine Books.