Xenobiotic interactions with soils are problematic due to the strong binding and slow release rates which increase their persistence in the environment. This study investigates the sorption of phenanthrene and steroid estrogens to various soil and clay mineral types with the intent to better understand sorption mechanisms. Batch sorption experiments demonstrate that several factors such as organic carbon type, organic carbon (OC) content, and clay mineral-soil organic matter (SOM) interactions play a role in the sorption of phenanthrene and steroid estrogens. Soil samples were characterized by elemental analysis and solid-state 13C Nuclear Magnetic Resonance (NMR). A positive correlation was found between steroid estrogen sorption affinity and the aromatic carbon content of mineral soils. However, phenanthrene sorption values could not be attributed to a specific soil chemical characteristic. The results of this study suggest that the physical conformation of SOM play an important role in sorption processes.