A thermoplastic composition is provided which exhibits desired levels of viscosity, dart impact strength, and flame retardancy. The composition includes respective amounts of a bulk vinyl aromatic-vinyl cyanide-rubber graft copolymer, an emulsion vinyl aromatic-vinyl cyanide-rubber graft copolymer and a flame retardant which contains an amount of a halogenated epoxy compound. The compositions are useful for making molded articles which exhibit desired levels of flame retardancy and impact strength. The thermoplastic compositions may also further contain respective amounts of non-epoxy halogenated compounds, flame retardant synergist such as antimony compounds, and drip suppressants such as fluoro polymers.