We studied the grafting of diblock copolymers onto mica surfaces in aqueous solutions. Because the copolymers are nonadsorbing on mica, grafting is achieved in the presence of adsorbing cationic surfactants. The surfactant film makes a sublayer onto which the hydrophobic moiety of macromolecules can end anchor. By using both a surface force apparatus (SFA) and an atomic force microscope (AFM), we studied how the interactions between the surfactant-coated surfaces are modified by the presence of copolymer and show how these modifications relate to changes in the morphology of the adsorbed surfactant film.