Abstract: Thermosetting polymers and the electrical laminates made therefrom are disclosed. The laminate comprises a cross-linked product of: a) one or more ethylenically unsaturated aromatic monomers, with fire retardation being optionally contributed by one halogenated monomer, b) a vinyl-terminated polybutadiene or butadiene-styrene copolymer containing either a urethane or an ester group, and c) a chemically modified polyphenylene ether resin, preferably low molecular weight chemically modified polyphenylene ether resin. It has been discovered that an unexpected combination of thermal, electrical, and mechanical properties are obtained from the composition recited herein. Therefore, the composition is ideally suited as a matrix polymer for electrical substrate applications.