This report describes a study designed to improve the interlibrary loan service offered by the I. D. Weeks Library at the University of South Dakota (USD); the study which examined both the actual time elapsed in filling interlibrary loan requests and the causes for delays. An introduction to the problem is provided; the library staffing and interlibrary loan process are described; and related literature is reviewed. In addition, a brief discussion of the study methodology describes the tracking of a total of 253 interlibrary loan request forms submitted to the Interlibrary Loan office during April 1986. Study results indicate that 28% of the requests were completed in one week (7 days), 61% were completed in two weeks (14 days), and 76% were completed in four weeks (28 days). Factors beyond the control of the library staff caused a delay in the completion of 19 of the 39 requests not completed after 28 days. It is recommended that borrowing materials for local USD patrons be made a clear priority for interlibrary loan, that regular follow-up procedures be instituted, and that an additional half-time staff position be added. Study results are presented in ten tables and interlibrary loan request and time study forms are included. A 20-item bibliography is also provided. (KM)