This paper summarizes research and publications on the benefits of providing elementary and secondary school media centers and libraries in developed and developing nations. Summaries of five research studies on the impact of media centers/libraries on teaching and learning provide information on research activities in the United States and Latin America. Also summarized are evaluative studies and reports on the effects of U. S. government programs developed under Titles II and IV-B of the Elementary and Secondary Education Act, which covered school library resources, textbooks, and other instructional material. A second section presents quotations from a number of formal professional statements which indicate that media centers can substitute for traditional classroom experience and can support independent learning. Publications from the United Nations Educational, Scientific, and Cultural Organization (UNESCO), the International Federation of Library Associations (IFLA), and other authorities are included; descriptions of specific media centers in various countries are also provided. A final section briefly outlines some examples of recent progress in school library programs in eight developing countries, while an amendment describes four education research projects in developing countries. Also presented are an introductory essay, an extensive abstract, a 30-item bibliography, and the addresses and contact persons for two relevant international library organizations. (ESR)