Abstract: Poly(vinyl chloride), when impact modified with a core/shell impact modifier whose shell is predominantly formed from a C.sub.1 to C.sub.4 alkyl methacrylate and whose core is a copolymer of butyl acrylate and a specific compositional range of certain higher alkyl acrylate monomers, exhibits improved toughness, especially at lower use levels of the modifier or lower test temperatures for the blend, than when the core of the impact modifier is either substantially formed from butyl acrylate alone or substantially formed from the higher alkyl acrylate alone.