The purpose of this report is to provide NASA with a rationale and recommendations for planning, implementing, and operating an Earth Observing System data and information system that can evolve to meet the Earth Observing System's needs in the 1990s. The Earth Observing System (EOS), defined by the EOS Science and Mission Requirements Working Group, consists of a suite of instruments in low Earth orbit acquiring measurements of the Earth's atmosphere, surface, and interior; an information system to support scientific research; and a vigorous program of scientific research, stressing study of global-scale processes that shape and influence the Earth as a system. The EOS data and information system is conceived as a complete research information system that would transcend the traditional mission data system, and include additional capabilities such as maintaining long-term, time-series data bases and providing access by EOS researchers to relevant non-EOS data. The Working Group recommends that the EOS data and information system be initiated now, with existing data, and that the system evolve into one that can meet the intensive research and data needs that will exist when EOS spacecraft are returning data in the 1990s.