An agent for treating keratin-containing fibers includes in a cosmetic carrier: (a) a cationic cellulose compound (b) a copolymer containing a structural unit of Formula (I), a structural unit of Formula (II), and a structural unit of Formula (III) in which R1 is a hydrogen atom or a methyl group, X1 is an oxygen atom or an NH group, R2 and R3 independently of one another are each a (C1 to C4) alkyl group and (c) a copolymer containing a structural unit of Formula (I) and a structural unit of Formula (IV) in which R4 is a hydrogen atom or a methyl group, X2 is an oxygen atom or an NH group, A is a (C2 to C3) alkylene group, and R5 and R6 independently of one another are each a (C1 to C4) alkyl group. Methods for treating keratin-containing fibers using the agents are also provided.
