This report summarizes the results of a program to characterize the trace element emissions from three coal-fired electric generating stations. A material balance approach was used for a quantitative examination of twenty-seven elements. An additional twenty-six elements were surveyed semiquantitatively. The trace elements can be broadly classed into three general groups; (1) those uniformly distributed in the coal ash, (2) those preferentially emitted with the fly ash, and (3) those emitted as vapors in the flue gas. The selection of stations using different coals with different boiler and particulate collection configurations provided a comparison of trace element emissions as a function of plant design and operating parameters. The overall report is presented in four volumes. Volume I compares the three stations. Volumes II, III, and IV give detailed results and descriptions of the methodology used for the individual stations.