This paper describes the development of a proposed Japanese Science Information System (SIS), a nationwide network of research and academic libraries, large-scale computer centers, national research institutes, and other organizations, to be formed for the purpose of sharing information and resources in the natural sciences, technology, the humanities, and the social sciences. It is noted that SIS will include sharing of primary documents, secondary information retrieval, provision of library holdings information, machine-readable library cataloging, and production of specialized databases. The paper is divided into nine sections covering: (1) background information; (2) SIS basic concepts; (3) SIS functions; (4) the structure of SIS, which is to include a Science Information Center (SIC) with planning, coordinating, service, research and development, and educational/training functions; (5) proposed SIC activities, service provision methods, and users, with a chart outlining an SIC development schedule; (6) the SIC database system, with a list of general, information retrieval, cataloging, and other system requirements; (7) the performance design of the SIC database system, with an outline of hardware, capacity, and access requirements in three stages of SIC development; (8) the SIS network system, which will include information retrieval, library cataloging and holdings information, and document delivery networks; and (9) the significance of SIS in information transfer in Japan. (ESR)