There is disclosed a novel mixture of polyhydroxy phenolic curing agents, such as novolac resins blended with a mixture of mono, bis and tris hydroxyaryl phosphine oxides for co-curing epoxy resins and imparting flame resistance thereto. A preferred composition includes a mixture of monohydroxyaryl, bishydroxyaryl and trishydroxyaryl phosphine oxide and a benzoguanamine/phenol/formaldehyde terpolymer which is used along with an epoxy resin to produce flame-resistant printed wiring boards without the use of halogens.