We have compared the interactions between Polyquaternium 10 and sodium dodecyl sulfate ( SDS) with similar complexes of mono and diquaternary aminoalkylcarbamoyl cellulose derivatives by measuring the surface tension of their aqueous solutions. The results indicate that reduction of surface tension of aqueous solutions occurs via the formation of highly surface active polymer-surfactant complexes. At approximately a 1:1 stoichiometric ratio of SDS to quaternary groups, a complex of low solubility forms which is more efficient at reducing surface tension than the surfactant alone. The ability of the polymer-surfactant complex to reduce surface tension appears to be independent of polymer architecture and dependent only upon adsorption of the surfactant species at the cationic polymer sites.