The Sixth International TIROS Operational Vertical Sounder(TOVS) Study Conference (ITSC-VI) was held in Airlie, Virginia, from 1-6 May 1991. The International TOVS Study Conferences (ITSC) continue to be held at approximately 18-month intervals. Since 1983 this Working Group of the International Radiation Commission has been convening users of the NOAA polar-orbiting satellite data to compare performance of schemes for retrieving thermodynamic properties of the atmosphere (such as temperature and moisture), to undertake case studies of the impact of soundings on numerical weather-prediction models, to define important directions for further research, and to formulate recommendations to the World Meteorological Organization. A summary and the recommendations of this conference are reported here.