A cost analysis of the problem of growing library collections shows that it is more desirable, economically and academically, to establish regional compact shelving facilities for infrequently used library materials than to discard the materials. This report develops and applies a cost model--based on the Palmour Cost Model--which examines the economic aspects of compact shelving and weeding in greater detail. The findings of cost analysis support the conclusions of prior analyses--there is a body of library material, defined by its average frequency of circulation, for which compact shelving facilities are the least expensive housing alternative. This report provides a description of the cost model and its parameters, as well as criteria for relegation and weeding. Appendices detail the methodology of the study. (Author/RAA)