A 2-day symposium, held to discuss progress made by the National Acid Precipitation Program (NAPAP) and other organizations in developing emission inventories. The symposium was sponsored by EPA's Air and Energy Engineering Research Laboratory, in cooperation with EPA's Office of Air Quality Planning and Standards, the U.S. Department of Energy, the National Oceanic and Atmospheric Administration, and NAPAP. The meeting was intended primarily for government, academic, and private sector individuals involved in developing or using emission inventories for acid deposition related activities. Topics addressed included historical emissions estimates, the 1980 and 1985 emission inventories, Eulerian modeling analysis, and uncertainties in emission inventories. The proceedings provide valuable documentation of results of efforts to date to develop emission factors and emission inventories for anthropogenic and natural sources.