The present invention is directed to a method of producing an adherent coating over untreated thermoplastic and thermosetting resinous substrates from a coating composition that includes a crosslinkable component and a crosslinking component that are mixed prior to application and applied over the substrate. The crosslinkable component includes a polymeric mix containing at least one crosslinkable copolymer polymerized from a monomer mixture comprising one or more ethylenically unsaturated monomers having on average 1 to 10, preferably 1 to 4 and more preferably 1 to 2 hydroxyl groups and a saturated hydrocarbon polymer. The crosslinkable component includes one or more cycloaliphatic polyisocyanate of the formula: R.sup.1--(R.sup.2--NCO).sub.n wherein R.sup.1 is a substituted or unsubstituted cycloaliphatic group, R.sup.2 is independently selected from a direct bond, a straight aliphatic group or branched aliphatic group, and wherein n ranges from 2 to 10. The method is well suited to produce adherent coatings on olefinic substrates such as those used in automotive and general commercial application without any pretreatment of the resinous substrates.