Factors related to the extraordinary growth and development of school libraries in the United States between 1945 and 1980 are reviewed in this report, which describes the establishment of standards for school library media centers, Knapp Foundation funding of school library projects, federal funding of school libraries, the professional certification of school library media specialists, the development of educational technology, and the participation of school libraries in networking. The results of a 1974 study of school libraries conducted by the National Center for Education Statistics (NCES) are presented in conjunction with a discussion of standards published in 1975 in "Media Programs: District and School." These standards cover school library media center staff, collections, and facilities, while survey results reported include hours of service, operating expenditures, the extent to which media programs complied with standards, and the extent of growth of the school library media center concept. Current trends briefly described include continued research, the development of systematic methods of planning and evaluation, the updating of selection criteria, and the assessment of alternative administrative structures, particularly the community/school or school/public library. A 26-item bibliography concludes the report. (Author/ESR)