Data, derived from the National Center for Education Statistics 1990-91 Schools and Staffing Survey, are presented about school library media centers and the support they receive. The focus is on the number of schools with library media centers, the level at which these centers are staffed, and the role library media centers and their staff play in schools. As of 1990-91, 96% of public and 87% of private elementary and secondary schools in the United States had a library or library media center. The expansion in library media specialists seen between 1960 and 1980 has slowed, and in the early 1990s school library media center staffing levels have not kept pace with increases in student enrollment. In the public sector, 8% of schools with library media centers did not employ some kind of media center staff, but over half of the smaller, elementary, and non-Catholic religious private schools had neither a librarian/media specialist nor a library aide. Few school principals reported that the school librarian or media specialist had much influence over curriculum decisions, although private school librarians were more likely to be acknowledged as influential. Twenty tables (and eight appendix tables) and four figures present survey data. (Contains 19 references.) (SLD)