The fourth study of federal libraries provided the first nearly complete statistical survey of all federal libraries in the continental United States and overseas. It was anticipated that the results of the study could serve as a landmark for future federal planning and as a guide for the library community in responding to related activities on the state and local levels. The survey identified 2,313 federal libraries. Data were collected on 2,145. Expenditures for reporting libraries totaled $191,825,822. The report includes summary statistics for all libraries, separate treatment of the national libraries, detailed findings for 1,386 libraries providing individual responses, and aggregate data for other reporting libraries. In the appendixes are given complete listings of the individual libraries queried, details of the survey methodology, and copies of the survey instruments. (Author/PF)