The National Center for Higher Education Management Systems (NCHEMS) has developed a library statistical data base which concentrates on the management information needs of administrators of public and academic libraries. This document provides an overview of the framework and conceptual approach employed in the design of the data base. The data contained in the management information system describes the environment, the overall resources, and the programmatic activities of the library. Environmental data for the library includes information which describes the external setting of the library, its internal organization, and the target group it serves. The overall resources of the library include four major types of data: collection resource data, human resource data, financial data, and facility resource data. The data concerning programmatic activities organizes the library into major activity or functional areas. For each of these a series of measure categories is used to describe and evaluate the activities of the library. These measures describe revenues and expenditures, personnel, facilities, activities, users, and outcome/performance of each of the activity areas. Changes and refinements are expected through practical applications of the system. Readers are advised to look at "Library Statistical Data Base Formats and Definitions," which gives the detailed set of data structures relevant to the categorizations of information, terminology and definitions employed in the design of the system. (Author/JPF)