Abstract: The invention relates to a process for flexibilizing epoxide resins by the addition of polymers which contain carboxyl groups by adding to the epoxide resins before they are cured, copolymers which are obtained by the conventional polymerization of:(a.sub.1) 40 to 87 weight percent of one or several alkyl esters of acrylic and/or methacrylic acid with 1 to 8 carbon atoms in the alkyl radical,(a.sub.2) 10 to 40 weight percent of vinyl acetate and/or acrylonitrile,(a.sub.3) 1 to 20 weight percent of acrylic, methacrylic and/or itaconic acid,(a.sub.4) 1 to 5 weight percent of glycidyl acrylate and/or glycidyl methacrylate, and(a.sub.5) 0 to 35 weight percent of acrylic and/or vinyl monomers, which are different from the monomers a.sub.1 to a.sub.