interlibrary loan, purchase on demand, patron driven acquisitions, cost per use, libraries
Many libraries are engaging in interlibrary loan purchase-on-demand without fully acknowledging all of the costs of adding such titles to their collections. This study compares the costs of monograph interlibrary loans and the costs of monograph accession, including staffing overhead costs for both. In order to be truly cost-effective, interlibrary loan purchaseon-demand titles must have a minimum projected circulation, depending on the base price to purchase the item. A review of current patron-driven acquisitions models associated with interlibrary loan purchase-on-demand is included.