Laboratory and field studies are underway to determine the effectiveness of activated carbon for removing volatile organic compounds from ground water. For fifteen C1 through C6 compounds being considered for possible regulatory action, the adsorption isotherm capacity ranges from approximately 1 to 125 mg compound/gram activated carbon, at an equilibrium concentration of 500 microgram/L. Because ground waters are typically low in background organic carbon, these adsorption isotherm data look promising for estimating adsorber performance. Additionally, physical and molecular properties of a contaminant may provide practical insight into its treatment by adsorption.