Atmospheric aerosols were collected during a 21 day period in late summer of 1976 in Charleston, West Virginia, using five dichotomous virtual impactor samplers simultaneously. The resulting coarse and fine aerosol were analyzed with a variety of physical and chemical methods: gravimetrically for total mass; by XRF for elements heavier than Mg; by proton induced gamma-ray emission for C, N and S; by ion chromatography for sulfate, nitrate and Na; and by ion selective electrode for ammonia. It was inferred that sulfur and nitrogen in the fine fraction were almost entirely in the form of ammonium sulfate, accounting for 41% of the total fine particle mass. Carbon was a large component of both fine and coarse particle mass, constituting 16% and 12%, respectively. Factor analysis of the data indicated that four factors were sufficient to satisfactorily represent the variance of 26 measured parameters. The factors are characteristic of crustal material, ammonium sulfate, automotive emissions, and an unidentified anthropogenic source or set of sources.