The main purposes of this study were to ascertain something of the quality of in-house use of materials in a science library, and to test the use of interviews as a method of measuring such use. Brief interviews were held with 414 users of the University of Illinois Veterinary Medicine Library (VML) between March 2 and May 13, 1987, to obtain information on the purpose of their visit and their use of library materials (other than reserve books) while in the VML. A count was also kept of the number of persons in the library and of the books and journals left on the tables. Of the four hypotheses tested, support was found for only one: that the number of items used in the library are at least twice as high when reported by the interviewees as when measured by table counts. It is suggested that future research might start with the hypothesis that people who use materials in a science library are doing so for substantive research and that typically they find what they seek. It is concluded that interviews are to be preferred to both table counts and self-administered questionnaires for collecting data. The report is supplemented with three tables and 18 footnotes/references, and a copy of the interview questions and the one-way frequency distribution of responses is appended. (CGD)