The purpose of this study was to evaluate the impact of Melvil Dewey's work in the American public library, both in Dewey's day and today. Using the writings of Melvil Dewey, as well as writings about him, this study examined what changes Dewey made and influenced as they specifically related to services provided to library users. This included studying Dewey's role in the organization of the library materials using the Dewey Decimal Classification System, the development of cooperative cataloging, and the creation and implementation of services to library users. The study focused on the impact of several theories that were the driving force behind Dewey's work in the library field. These theories contained several components, including the need for an organized library and the role of the library as a companion to public schools in the education of the common man. Dewey's work also focused on the need for the library to provide information to the user efficiently and with careful expenditure of the library's resources, both human and financial. (Contains 30 references.) (AEF)