A composite article comprises a first layer resulting from the reaction of at least one ethylenically unsaturated monomer and a second layer different than the first layer and resulting from the reaction of an isocyanate-reactive resin and a polyisocyanate. Adhesion promoter is dispersed in at least one of the first layer and the second layer. The adhesion promoter comprises a first reactive end group selected from the group of an ethylenically unsaturated monomer, an ethylenically unsaturated acrylate monomer, an ethylenically unsaturated methacrylate monomer, or a combination thereof and a second reactive end group that reacts with isocyanate. The adhesion promoter reacts into the first and second layers through differentially reactive groups such that the adhesion promoter is compatible with the first and second layers to improve adhesion therebetween. A method of forming the composite article is also disclosed.