The report, prepared for the National Acid Precipitation Assessment Program (NAPAP), identifies the most appropriate ammonia (NH3) emission factors available for inclusion in the 1985 NAPAP Emissions Inventory. NH3 emission factors developed for several new NAPAP source categories were compared with factors developed for other inventories. Although many of the NH3 emission factors presented in the report have low quality ratings, those factors determined to be the most accurate for each category were selected for application to the Inventory. Emissions factors and estimates of NH3 emissions are included for human breath, cigarette smoke, and human perspiration but, for reasons discussed, are not included in the Inventory. NH3 emissions from wildlife excrement were investigated; while there is not universal agreement, the report and other NAPAP research conclude that the net contribution to ambient NH3 is zero. The total NH3 emissions included in the Inventory are 1,685,473 tons per year. The most significant NH3 sources, accounting for 83% of the total emissions, were livestock wastes, wastewater treatment, and ammonium nitrate manufacture.