The Mountain-Valley Library System (MVLS), a cooperative of 19 public and academic libraries in nine northern California counties, performed a cost study of its interlibrary delivery system during fall, 1977. This report discusses the results of item count for all 62,000 materials handled in the system during a two-month sample period and projects a yearly volume by shipping library and by material category. Costs are projected for continuing the service during FY 1978-1979 and FY 1979-1980 using a dedicated van system. These costs are compared to projections for use of other carriers including United Parcel Service. Conclusions show that, for the desired speed of delivery arrival, packaging time costs, and integrity of the shipment method, the use of dedicated delivery vans is the most cost efficient delivery. Schedules, routes, mileage charts, and sample forms and instructions used during the study are appended. (Author/JPF)