This invention relates to compositions and methods for improving the adhesion of resin compositions to substrate materials. More particularly, the invention relates to compositions and methods for improving the adhesion of ROMP compositions to substrate materials using an adhesion promoter composition, where the adhesion promoter composition comprises a pre-reacted mixture comprising at least one compound containing at least two isocyanate groups and at least one compound comprising a heteroatom-containing functional group and a metathesis active olefin, where the adhesion promoter composition is storage stable and/or possesses in-resin storage stability when added to a resin composition, particularly a cyclic olefin resin composition, such as a ROMP composition. The polymer products produced via ROMP reactions of the invention may be utilized for a wide range of materials and composite applications. The invention has utility in the fields of polymer and materials chemistry and manufacture.