A knowledge of environmental soil chemistry is paramount to predicting the fate, mobility and potential toxicity of contaminants in the environment. The vast majority of environmental contami-nants are initially released to the soil. Once a chemical is exposed to the soil environment a myriad of chemical reactions can occur that may increase/decrease contaminant toxicity. These reactions include adsorption/desorption, precipitation, poly-merization, dissolution, complexation, and oxidation/reduction. These reactions are often disregarded by scientists and engineers involved with environmental remediation. Under-standing these processes enable us to better predict the fate and toxicity of contaminants and provide the knowledge to develop scientifically correct, and cost-effective remediation strategies.