Batch equilibrium and column miscible displacement techniques were used to investigate the influence of an organic cosolvent (methanol) on the sorption and transport of three hydrophobic organic chemicals (HOCs) - naphthalene, phenanthrene, and diuron herbicide - in a sandy surface soil (Eustis fine sand). Equilibrium sorption constant (K) values calculated from batch and column data exhibited an inverse log-linear dependence on the volume fraction (fc) of methanol in the mixed solvent. The slope of the log-linear plot was approximately equal to the logarithm of the ratio of the HOC solubilities in neat cosolvent and water. K values obtained from breakthrough curves were comparable to those estimated from equilibrium sorption isotherms. Long-term exposure to methanol-water mixtures had little effect on sorption and transport properties of the soil, but column retardation factors were influenced by the short-term solvent exposure history prior to solute elution.