The interlibrary loan (ILL) fill rate for lending is, arguably, the most important statistic used toevaluate the success and reliability of the lending service. This fill rate percentage, however, isactually heavily influenced by factors external to the academic library’s ILL department. The fillrate metric, alone, does not tell the whole story. A deeper dive into lending practices and theassociated data and statistics can help elucidate factors that are negatively impacting it. Thisinformation is essential for ILL practitioners as they can use it to institute measures tocontinuously improve the fill rate by implementing best practices.