Abstract: Core-shell ABS copolymers having an SAN shell completely surrounding the diene core are provided by melt blending an aliphatic diene polymer with an SAN copolymer, said copolymer containing functional groups capable of reacting with the diene polymer. For example, the SAN copolymer may contain azide groups capable of reacting with the olefinic groups in the diene polymer, or both the SAN copolymer and the diene polymer may contain other functional groups capable of interreaction, such as acidic (e.g., maleic anhydride) groups in the diene and epoxy (e.g., glycidyl methacrylate) groups in the SAN copolymer.