We obtained yard soil and indoor dust samples from 10 houses in Tucson, Arizona. All samples were sieved to <63 microns and analyzed for 29 elements via ICP-MS following nitric acid digestion. We calculated the ratios of the concentration of elements in house dust to the exterior soils. The geometric mean of the ratios ranged from 0.55-24.21. Ratios greater than 1 can indicate both indoor and outdoor sources other than soil track-in on footwear or from aeolian resuspension. The elements with the lowest ratios were manganese and beryllium. The elements with the highest ratios were zinc, silicon, tin and sodium. In general, the geometric standard deviations of the ratios are the highest for those elements that are derived from atmospheric sources. These results are very different from similar samples collected in Ottawa, Canada, indicating that they are specific to the region due to unique soil mineralogy and contaminant sources.