Abstract: The adhesion of inorganic substrates such as glass, silica, clay, alumina, or steel, to organic resins such as polysulfides, polyolefins, polyesters, polyurethanes, epoxy resins, or EPDM rubber is improved with the use of compositions comprising from about 5 to 95 weight percent of a component selected from a first group consisting of methacryloxyalkyltrialkoxysilanes, mercaptoalkyltrialkoxysilanes, vinyltrialkoxysilanes, vinyltrihalosilanes, and alkylvinyldihalosilanes wherein each alkyl or alkoxy group has 1 to 3 carbon atoms inclusive, and from about 5 to 95 weight percent of a second component selected from a second group consisting of alkyltrialkoxysilanes, dialkyldialkoxysilanes, trialkylalkoxysilanes, trialkoxysilanes, tetraalkoxysilanes, aryltrialkoxysilanes, alkylaryldialkoxysilanes, and diaryldialkoxysilanes, wherein each aryl group is phenyl or para-tolyl, each alkyl group has 1 to 8 carbon atoms inclusive, and each alkoxy group has 1 to 3 carbon atoms inclusive.