Cosmetic composition containing a cationic polymer and an acrylic terpolymer, and use of this composition for the treatment of keratinous material. The present application relates to cosmetic compositions containing, in a cosmetically acceptable aqueous medium, at least one cationic polymer and an acrylic terpolymer, as well as to the use of these compositions for treating keratinous material. The acrylic terpolymer comprises: a) about 20 to 70% by weight of a carboxylic acid containing .alpha., .beta.-monoethylenic unsaturation; b) about 20 to 80% by weight of a non-surfactant monomer containing monoethylenic unsaturation, which is different from a), and c) about 0.5 to 60% by weight of a nonionic urethane monomer which is the product of reaction of a monohydric nonionic surfactant with a monoisocyanate containing monoethylenic unsaturation. The invention relates in particular to hair products containing, when they are in leave-in form, quaternized or non-quaternized vinylpyrrolidone/dialkylaminoalkyl acrylate or methacrylate copolymers or quaternized vinylpyrrolidone and vinylimidazole polymers.