The Interlibrary Loan (ILL) Section of the UCLA Biomedical Library was studied in an attempt to develop a methodology for analyzing interlibrary loan associated costs that would be generalizable to other libraries. Other objectives included developing standards of performance to monitor staff productivity and correcting imbalances in the flow of requests. To these ends, a full task analysis was performed of all functions carried out in the section. Thirty-one activities, comprised of 87 tasks, were identified. For each task, sample size, performance standard, and percent of task application to each activity were determined; for each activity, the additional factors of level of staff and activity cost per request were assigned. The activities were grouped into five functional areas: (1) receiving, (2) filling a book request, (3) filling a journal request, (4) location/referral service, and (5) administration and support. A total ILL transaction cost of $1.80 resulted from adding cumulative functional labor costs and nonlabor costs. However, certain qualifications should be made: a weighted average concept was used; only direct and on-going costs were considered; the monthly volume of requests used was averaged; the time period of the study and the organization of the section affected the findings. In light of these conditions and new changes in the library, a future study is planned. An appendix of flow charts and data tables is provided. (JD)