A composition includes specific amounts of a poly(phenylene ether), a poly(phenylene ether)-polysiloxane block copolymer, a homopolystyrene, a flame retardant, and a reinforcing filler. The composition exhibits a desirable balance of flame retardancy, heat resistance, stiffness, and melt flow. Articles that can be prepared from the composition include frames and chassis of office equipment, fuser module parts for printers, copiers, and facsimile machines, cooling fan blades, cooling fan housings, parts for automotive kinetic energy recovery systems, and parts for electric vehicle junction boxes.