The adsorption of polyethylene glycol dodecyl ether (C(12)E(25)) On hydrophobic polystyrene latex particles of low surface charge density has been examined as a function of the surfactant concentration by determination of the particle hydrodynamic radius (R(H)) using dynamic light scattering and of the adsorption isotherms by a surface tension method. The adsorption is driven by hydrophobic interaction between the alkyl tails of C(12)E(25) and the pendant polymer chains at the latex particle surface. The extended poly(oxyethylene) (POE) chains coil to form a hydrophilic surface around the latex particles. The conformation of the POE chains dominates the structure of the adsorbed layer, and this leads to similar adsorption behavior in both the R(H) trace and the adsorption isotherm, independent of added salt or the temperature.