This report summarizes the 1987 research activities of each Task Group involved in the National Acid Precipitation Assessment Program. The Emissions and Controls Task Group provides data on past and current emissions of gases and particles that contribute to acid precipitation, and its primary contribution in 1987 was to complete a 1985 database on over 11000 point sources which is used as input for the Regional Acid Deposition Model. Findings of the Task Group on Atmospheric Chemistry indicate that natural emissions of sulfur in the eastern U.S. are about 0.1 percent of anthropogenic emissions. The Atmospheric Modeling and Transport Task Group completed a major phase of development of the state of the art Regional Acid Deposition Model, and plans were begun for a two year field program to evaluate the model's performance. The Atmospheric Deposition and Air Quality Monitoring Task Group continued to publish its summaries of wet deposition in the United States. One finding is that concentrations of ammonia, nitrate, and sulfate in wet deposition in the eastern United States are considerably higher than at remote stations around the world. The Terrestrial Effects Task Group continued to examine the interactions between acidic deposition and ozone, drought, insect infestations, and disease organisms for both crops and forests. The Aquatic Effects Task Group continued to collect and analyze data from the National Surface Water Survey concerning sources and biological consequences of acidification. They also are examining possible side effects of mitigative liming. Finally, the Task Group on Effects on Materials and Cultural Resources continued efforts to develop dose-response functions to relate changes in materials (e.g. carbonate stone) degradation to acidic deposition and associated pollutants.