This study evaluated procedures for estimating adsorption of polycyclic aromatic hydrocarbons (PAH) onto soil from knowledge of soil organic carbon content and physico-chemical properties or structural characteristics of PAH. The study also entailed an experimental investigation to observe the manner in which naphthalene moves through unsaturated soil. It was found that an approximate value for adsorption coefficients for PAH onto soil can be obtained from readily available physico-chemical properties or structural characteristics for PAH, and correlation with information on soil organic carbon content. A laboratory apparatus was assembled in order to observe organic solute transport through unsaturated porous media, and laboratory experiments were performed to evaluate transport of naphthalene in unsaturated soil. Two tests were performed of approximately fifty days duration each. The tests were configured to observe naphthalene adsorption and breakthrough, followed by observations on naphthalene desorption characteristics. Naphthalene breakthrough was observed in tests with sterilized soil, and approximately 60% of naphthalene applied to the column was eventually eluted during desorption. This value of retardation coefficient compared favorably to that which was predicted from determination of naphthalene adsorption coefficient. Hydrodynamic dispersion coefficients were determined for transport of both chloride ion and naphthalene under conditions of both step increase and step decrease in concentration. The experimental portion of this investigation evaluated transport through unsaturated soil because groundwater contamination problems often originate in the unsaturated zone, and because relatively little information exists regarding the manner in which organic solutes are transmitted through this zone to the water table. 115 references, 22 figures, 20 tables.