ILL is often the most fundamental access service for users seeking to acquire research materials. The interlibrary loan fill rate for lending is, arguably, the most important statistic used to evaluate the success and reliability of the lending service. This fill rate percentage, however, is actually heavily influenced by factors external to the academic library's ILL department and does not, alone, tell the whole story. A desire to increase the lending fill rate requires an investigation into the reasons why requests received from borrowing libraries go unfilled. A deeper dive into lending practices and the associated data and statistics can help elucidate the factors negatively impacting it. This presentation will describe the steps taken, relating to cross-training ILL staff, implementing new lost/missing protocols, setting deflections, updating local holdings records, etc. to better understand the factors that negatively impact the lending fill rate and will detail best practices for improving it.