Compounds useful as adhesion promoters for thermally cured thiolene adhesives include a) acrylic or norbornene acid phosphate esters such as ##STR1## b) maleic, acrylic, methacrylic, norbornene dicarboxylic, and fumaric acids and half acid esters and peresters of maleic fumaric and norbornene dicarboxylic acids; and c) norbornene, acrylic or methacrylic silanes having two or three hydrolyzable groups bound to the silicon atom thereof, such as 5-(triacetoxysilyl) norbornene.The adhesion promoters may be employed as surface primers for conventional thiolene compositions. Alternatively the thiolene compositions themselves may be modified by addition of 0.1 to 10% by weight of the adhesion promoter. Preferred thiolene compositions employ norbornene functional ene ingredients.