The Atacama Desert of northern Chile is the driest and oldest landscape surface on Earth. Precipitation in the hyperarid core of the desert is less than a few mm per decade, and these conditions are thought to have persisted for the last 10 million years. As a result, soils in the Atacama are unique on Earth. Soils in the core of the Atacama contain up to 15% nitrate and also have measurable concentrations of iodate and perchlorate. The most dominant soil salts in the Atacama, however, are sulfates (mostly gypsum and anhydrite) in the core of the desert and carbonate (calcite) along the outer margins, where plants are present and precipitation is greater than ~15 mm/yr. The origin of soil salts in the Atacama has been debated by scientists for over 100 years. Potential sources for pedogenic salts include: evaporite playas, marine aerosols, volcanic emissions, weathering of local bedrock, and far-traveled atmospheric dust. Over the last 5 years we have systematically sampled soil salts along numerous transects in the Atacama Desert and analyzed their isotopic compositions to identify the origin and transport paths for these pedogenic salts. We used δ34S to identify the origin of sulfates, 87Sr/86Sr to track to source of Ca in sulfates and carbonates, Δ17O values of nitrate to identify the relative input of atmospheric nitrate, and we used the δ13C and δ18O isotopic values of soil carbonate to identify the controls on soil carbonate formation. Isotopic results indicate an atmospheric source for soil nitrate, local evaporite playas as the main source for soil sulfates, with marine aerosols being an important source in some locations, and a strong link between plants and the formation of soil carbonate along the outer margins of the Atacama.