Agents for treating keratin-containing fibers, in particular human hair, comprising a cosmetically acceptable carrier, and: (a) at least one strengthening anionic copolymer, comprising at least one structural unit of formula (I) and at least one structural unit of formula (II) and at least one structural unit of formula (III), and (b) at least one polymer comprising at least one structural unit of formula (M1), produce an excellent hold of a shape imposed on the fibers, e.g. a hairstyle. The keratin-containing fibers are given a pronounced shine and feel soft.
