Different modes of interaction of polymers and polyelectrolytes with partially soluble and nonsoluble colloids, respectively, aluminum oxide at pH 5, and a polystyrene latex bearing amidine surface groups were investigated with the aim of determining the influence of the presence of aluminum ions on the polymer adsorption or deposition on the two types of material. Information on the nature of the interaction was obtained by comparing the electrophoretic mobilities of the polymer-coated colloids. Specific adsorption interactions could be demonstrated in the case of neutral polyacrylamide where the polymer solubility was independent of the electrolyte composition of the medium. Identical deposition of the complexed form of polyacrylic acid on the two colloid surfaces was observed. The adsorption of the complexed form of partially hydrolyzed polyacrylamide was found to proceed in the same manner and these results were attributed to a strong decrease in polyelectrolyte solubiiity. Studies of this type are relevant to environmental problems such as colloid-mediated retention or migration of ionic pollutants.