A workshop on the National Polar-orbiting Operational Satellite System (NPOESS) ozone measurements requirements was held August 30-31, 1995, at the NOAA Science Center, Camp Springs, Maryland. The workshop was sponsored by the Office of Research and Applications of the National Environmental Satellite, Data, and Information Service as part of an internal concept study (ICS) for the Integrated Program Office (IPO). The purpose of the workshop was to acquire scientifically-based ozone measurements requirements to be carried out by the NPOESS. These and other ozone-related requirements were to be presented to the IPO, to be considered in developing the operational satellite system payload. Participants at the workshop represented a cross-section of users of satellite ozone data involved in a variety of studies including ozone trends and climate change. Participants were scientists from government agencies and universities in addition to the scientists carrying out the IPO study. Highlights of the workshop were (1) completion of requirements for the ozone environmental data record (EDR) for the next version of the interagency operational requirements document (IORD); (2) presentation and discussion of the final report of the Climate Suite Internal Concept Study conducted jointly by NOAA/Office of Research and Applications, DoD/National Research Laboratory, and the University of Maryland, Department of Meteorology; (3) recommendations and justification for measurements other than ozone but related to ozone photochemistry and climate effects, including stratospheric aerosols N2O, stratospheric and upper tropospheric water vapor, ClO (or ClONO2), and solar flux; and (4) agreement that user scientists must be involved in the instrumental aspects of the NPOESS definition process.