The Source Signature (squared S) sampler was developed to characterize the carbon (C) and elemental components in fine particulate emissions from a residential wood burner. The hot exhaust is sampled and diluted with filtered air to simulate normal diffusion. The resulting aerosol is passed through a 2.5-mu m cyclone and the remaining particles collected on two parallel 1-mu m filers, one quartz and one Teflon. The quartz filter allows analysis of carbon content and the Teflon filter allows elemental analysis by x-ray fluorescence. Both filters are also weighed to determine the mass-emission rate. The test program's main objectives were (1) to test and improve the performance of the method, and (2) to make a laboratory measurement of the elemental composition including the carbon component to establish a source signature for use in receptor modeling.