Use studies were conducted at the main libraries and science branches at the Davis and Santa Cruz campuses of the University of California to gather data for use in the detailed planning for establishing regional compact shelving facilities for infrequently circulated library material. Analysis of preliminary data on the three areas examined--unrecorded use, browsing, and immediacy of need--suggest that (1) collection usage may be six times greater than indicated by circulation statistics; (2) unrecorded use is not synonymous with at-the-shelf discovery; (3) differences exist in recorded and unrecorded use rates between broad categories of materials; (4) techniques are available for recording use of materials consulted in the library and reshelved by library staff; (5) some library users are aware of differences in the immediacy of their needs; and (6) further investigation of browsing and/or immediacy of needs is unwarranted at this time. This report provides an executive summary as well as a detailed description of the methodology and findings in each study area. Appendices include reports on a questionnaire response rate experiment and a regression analysis of the relationship between circulated and unrecorded use, a glossary, and a list of 27 references. (RAA)