The adsorption behavior of a series of nonionic polyoxyethylated nonyl phenol surfactants having same hydrocarbon chain length but varying oxyethylene chain has been studied spectrophotometrically at the silica-cyclohexane interface. The adsorption density is found to be independent of the number of oxyethylene units throughout the adsorption isotherms, except at higher surface coverage, where the adsorption density decreases with the increase in the number of oxyethylene units. The settling rate of the silica particles in cyclohexane decreases with the increase in adsorption density as well as oxyethylene chain length. On the other hand, the sediment volume decreases with the increase in the adsorption density, with a minimum for the surfactant having the least number of oxyethylene units. Surfactants with a longer oxyethylene chain partitions preferentially to the bulk solvent at higher concentrations, as I result of the change in the polarity of the medium. On the basis of adsorption density, settling rate, and sediment volume data, a model for the mechanism of stabilization of silica-cyclohexane dispersion has been proposed. The aromatic ring of the surfactant is assumed to be anchored on the silica surface through specific interaction with silanol hydrogen, while its nonyl and oxyethylene chains are suspended in the bulk cyclohexane solution. The protruding oxyethylene chain offers a strong steric resistance for particle-particle association leading to the stabilization of the silica-water dispersion.