A curable composition including a polymer comprising, as copolymerized units, a monomer having carboxylic acid groups, anhydride groups, or salts thereof, and at least one of certain hydroxyl group-comprising monomers wherein the ratio of the number of equivalents of the carboxylic acid groups, anhydride groups, or salts thereof to the number of equivalents of the hydroxyl groups is from about 1/0.01 to about 1/3, and wherein the carboxylic acid groups, anhydride groups, or salts thereof are neutralized to an extent of less than about 35% with a fixed base is provided. Also provided is a method for treating a substrate with the curable composition and a substrate bearing the cured composition.