A composition for and method for bonding a substrate. In general, applied to a substrate will be a primer composition that includes an adhesion promoter, which is an adduct prepared by the reaction of at least one aromatic polyisocyanate compound, with an active hydrogen containing moiety of an organofunctional silane, and a prepolymer derived from the reaction of at least one aliphatic polyisocyanate and a polyol, and is at least partially reacted with an active hydrogen containing moiety of an organofunctional silane.