Determining if items are available is a major part of interlibrary loan work. Many libraries try to minimize staff time spent on determining availability by investing in circulation-based resource-sharing systems that require a major investment in time and funds, and then work only for the libraries within the circulation-based system. The IDS Project created a new solution, a Lending Availability Service, to automatically determine availability through software that is integrated within the resource-sharing software ILLiad. The Lending Availability Service determines availability for any requests a library receives, and it can automate portions of the ILL workflow that require determining whether an item is on the shelf or in a collection that can be lent. The Lending Availability Service is highly configurable and was designed with ILL workflows in mind. It overcomes problematic areas in workflows to allow for highly optimized resource sharing through automatic lookups of availability.