Abstract: A curable composition of a catalytic reactive polymeric component bearing at least one pendant catalytic, anionic group such as --SO.sub.3 H and a plurality of pendant carboxyl containing coreactive groups such as --COOH and having dispersed therein a coreactive component of a monohydroxide or monoepoxide of a hydrocarbyl ether is relatively stable at room temperatures but cures upon the application of heat to form a strong, solvent-resistant film. For example, a solution of a copolymer of methyl acrylate and 2-sulfoethyl methacrylate and a t-butyl glycidyl ether coreactive component can be applied to a suitable substrate and heated to form a cured film.