Toward a theory of collection development

Libraries exist because of the benefits they make possible to patrons and others, which benefits derive essentially from libraries' collections. A library collection should be seen as an investment. Benefits are returned on that investment and may justify the investment. Benefits remain potential benefits until use of materials in the collections results in actual benefits. Because of the role of benefits in justifying the investment, and the role of collections in providing benefits, this paper contends that collection development is the critical function in a library. Support is developed for this contention, which contributes to a theory of collection development, by focusing deserved attention on collection development, on library collections, on the related issues of benefits and return on investment, and on the question, Why do libraries exist? Finally, the discussion attempts to convince senior library managers and others of the obligation to ask if the benefits deriving from a library collection justify the dollars invested in that collection.