Sampling and analytical methods to measure atmospheric concentrations of sulfur, sulfates and related species are compared for aerosols collected in New York City, Philadelphia, PA., South Charleston, WV., St. Louis, MO., Glendora, CA., and Portland, OR. For the aerosol sampling, dichotomous samplers that were equipped with virtual impactors were used to separately collect fine (less than 3.5 micrometer) and coarse (greater than 3.5 micrometer) particles on membrane filters. Both size fractions were analyzed by energy dispersive x-ray fluorescence spectroscopy to determine the total amounts of sulfur and other elements, and the samples were analyzed by an Ion Chromatograph and by the thorin titration method to determine sulfate. These analyses reveal that more than 70% of the sulfur occurs in the fine particle fraction for at least 90% of the samples. Sulfate typically accounts for about 40% of the mass of the fine particle fraction, and in some instances it accounts for more than 50%. For the fine particle fraction, the ratio of the sulfate and the sulfur mass concentrations is 3.04 + or - 0.15, which is in excellent agreement with the value of 3.00 for sulfate. To test for the existence of sulfite ions in the samples, a cold extraction procedure was developed, which minimizes the conversion of sulfite to sulfate. Analysis for sulfite using the Ion Chromatograph indicates that less than 2% of the sulfur collected in South Charleston, WV. and Philadelphia, PA. is in the form of sulfite.