Adsorption levels of an anionic and an amphoteric foam-forming surfactant were measured in clean, water-wet and in asphaltene-treated, more oil-wet Berea sandstone, either oil-free or containing waterflood residual saturations of dodecane, a light crude oil, or a heavy crude oil. The affinity of both surfactants for the solid/liquid interface, or the adsorption density, was higher on the more hydrophobic sandstone surfaces. However, the asphaltene-coated Berea sandstone provided less solid surface area for surfactant adsorption. Normalized to unit mass of rock, adsorption of the anionic surfactant was higher and adsorption of the amphoteric surfactant lower in the asphaltene-treated cores. The presence of oil had no effect on surfactant loss in clean or asphaltene-treated cores. Solid-surface charge measurements indicated that the increased adsorption density on the asphaltene-treated surfaces cannot be accounted for by electrostatic interactions. Hydrophobic interactions are suggested as likely adsorption mechanisms.