Water-soluble copolymers and terpolymers as stabilizers for aqueous building material systems and water-based paint and coating systems are described. Advantages of the copolymers and terpolymers used according to the invention compared to conventional products are firstly the very good stabilizing properties of the building material systems or water-based paint and coating systems produced correspondingly and secondly the fact that the viscosity of the systems is barely increased, so that these have excellent processability.