Document delivery support for selective dissemination of information (SDI) services provided by the Center for Information Services, University of California at Los Angeles, was measured by the following: (1) Obtaining copies of all steady-state SDI searches from Biological Abstracts'"BA Previews" data base delivered to the University of California at Berkeley campus; (2) Determining potential availability of the citations by look-up in the University of California at Berkeley library catalogs; and (3) Determining actual availability by placing hands on the cited publications. Twenty-three SDI printouts containing 680 citations, for thirteen users, were studied, 6 0/0 of the total citations were found on the shelves. Of the potentially-available citations, 85.4 0/0 were found on the shelves. This methodology is suggested as an unobtrusive measure of the extent to which a library's collection can support its patrons' current research interests in a variety of subject fields. (Author/SJ)