A polyester molding composition reinforced with fiber glass or other silica based filler which has color stability at relatively high temperatures and comprises (a) from 40 to 97 weight percent of a polyester resin; (b) from about 3 to about 60 weight percent fibrous glass or silica based filler or mixture; (c) less than about 5 percent by weight additional ingredients which include a combination of stabilizers consisting essentially of an acidic quencher, a thioester and a phosphonite and (d) optionally from 2 to 30 weight percent of a flame retarding composition.