This research is a significant contribution to our understanding of missing items in the CUL collection. The validation study was useful in determining the availability of CUL materials in the open stacks; when patrons seek a monograph in the stacks, they are able to locate that item 96.4% of the time, overall. This translates into a projected loss rate of 3.6% of materials in the open stacks. That is the aggregate estimate. The loss rate varies by location. There is no significant difference in the accounted for rate in EAST libraries that tattle-tape versus EAST libraries which do not tattle-tape. Our research suggests it is time to question the notion that tattle-taping is the primary and best method available to improve the usability of open stacks.