This paper reviews the first year (February 1995-January 1996) of data on particulate composition, centering on the prevalence of elements and organic/elemental carbon. Typically fine mass samples are 40 percent organic carbon, 10 percent elemental carbon, and about 15 percent other elements. Carbon concentrations rise in the late fall and winter, coincident with low wind speeds that may allow automotive emissions to be trapped near the surface. At the same time, carbon rises as a proportion of the fine mass. There is some evidence of leaded gasoline use in Phoenix. Higher wind speeds in the spring and summer result in a greater proportion of crustal elements and sulfur. Comparisons of measurements from the DFPSS (cyclone) and VAPS (virtual impactor), indicate biases consistent with the notion that the cyclone is less efficient at effecting the 2.5 micrometer size cut, allowing larger particles through to the fine mass filters.