||Atmospheric pollution is deposited on the forests of the eastern United States in a variety of forms. Concern has been raised that the exposure to and deposition of these atmospheric pollutants may play a role in the decline of these forests. The Mountain Cloud Chemistry Project (MCCP), sponsored by the U.S. Environmental Protection Agency (EPA) and the National Acid Precipitation Assessment Program (NAPAP), has studied the exposure and deposition of atmospheric constituents to these forests. Research scientists and technicians of the MCCP have measured the concentrations of atmospheric pollutants at six remote monitoring stations for four growing seasons (1986-89). Measurements of ozone, sulfur dioxide, oxides of nitrogen, hydrogen peroxide, cloud and rain water ions, meteorological parameters, and other parameters of interest were collected at sites in Howland, ME; Mt. Moosilauke, NH; Whiteface Mt., NY; Shenandoah Park, VA; Whitetop Mt., VA; and Mt. Mitchell, NC. The report served to document the type and amount of data collected for the Mountain Cloud Chemistry Project during the four warm seasons between 1986 and 1989. Details are presented on the locations of the six research/monitoring sites, the types of measurements made, the periods of record, the quality of the data, and the availability of the data.