This paper examines the functions and services of public, academic, special, and school libraries; identifies similarities and differences that might exist among them; looks at basic functions and how they relate to the characteristics of the library's clientele; determines to what extent the services have been cost-effective; and explores alternative sources and programs for present services. The shift of libraries from the concept of a library-centered organization to that of a user-oriented organization is emphasized. (Author/JAB)