Cloudwater and aerosol samples were cullected during three 1987 summer events at Whiteface Mountain, New York. Dominant inorganic components in Cloudwater were SO₄²⁻, NO₃⁻, H⁺, and NH₄⁺. Maximum levels were 978, 256, 421, and 832,μeq l⁻¹, respectively. pH values in Cloudwater ranged from 3.1 to 4.4. Large variations in concentrations were found, which can best be explained, on the basis of back-trajectory analysis, by different origins of air masses. A concave concentration versus a time profile for the ionic concentrations was observed, possibly as a result of dilution and concentration as liquid water content changed over the life of the cloud. Dominant components of the aerosol were NH₄⁺ and SO₄²⁻. Changes in the gas-phase concentrations of SO₂, O₃, and H₂O₂ during a cloud event indicated a considerable S(IV) oxidation potential by H₂O₂. Free acidity (H⁺) was 32 – 81% of the total acidity. Carboxylic acid concentrations were dominated by formic acid (13.9 – 39.9μeq l⁻¹), acetic acid (5.1 – 14.7 μeq l⁻¹ oxalic acid (2.9 – 19.3 μeq l⁻¹), malonic acid (3.9 – 14.7 μeq l⁻¹, and pyruvic acid (2.4 – 8.6 μeq l⁻¹); these acids have accounted for 7 – 15% of the dissolved organic carbon and up to 22% of the free acidity. Multivariate factor analysis yielded three components that accounted for 91 % of the variability of all the parameters: transported acid component, combination of fossil-fuel combustion and automobile emission, acid nontransported biogenic component. Primary pollutant concentrations and photochemical activity during long-range transport were the major factors in controlling the chemical species concentrations at the downwind site.