The report documents the compilation of a 1980 emissions inventory for use in the National Acid Precipitation Assessment Program (NAPAP). The current inventory (Version 3.0) contains point source data for over 50,000 plants (with over 201,000 emission points) and area source data for the 3,069 counties in the 48 contiguous states and the District of Columbia. Emissions of SO2, NOx, VOC, CO, and particulates are included in the inventory, but the report focuses on SO2, NOx, and VOC which are of primary interest for acid deposition research. NAPAP Version 3.0 emissions of SO2, NOx, and VOC are 27.1, 23.7, and 23.3 million tons per year, respectively. Summaries of emissions by source category, geographic region, state, fuel type, season, and stack height range are given, along with emission density maps and fuel use summaries. Emissions in the NAPAP data base are in reasonable agreement with Work Group 3B and EPA/OAQPS emissions trends estimates. NAPAP fuel use data show reasonable agreement with fuel values in DOE's State Energy Data Report. Version 3.0 of NAPAP represents a detailed inventory of emissions on a national scale; however, it should be noted that additional improvements are planned.