A process for producing a thermoplastic resin having excellent impact resistance and processability, which comprises: polymerizing an aromatic monovinyl monomer and a vinyl cyanide monomer in the presence of an aqueous elastomeric latex, mixing with agitation the resulting copolymer latex with an aromatic monovinyl monomer and a vinyl cyanide monomer in the presence of a polyalkylene oxide and a coagulant to give a stable suspension phase, and polymerizing the mixture, and said thermoplastic resin thus produced, and a composition comprising said thermoplastic resin and a copolymer produced from an aromatic monovinyl monomer and a vinyl cyanide monomer.