Curable water-base compositions are prepared by combining a thermosetting acrylic polymer or an aminoplast composition with a water-soluble composition prepared by the reaction of an N-3-oxohydrocarbon-substituted acrylamide (preferably diacetone acrylamide) with an aldehyde (preferably formaldehyde) in the presence of an alkaline reagent. "Prepregs" can be prepared from filled water-base compositions of this type, preferably in aqueous solution with a free radical polymerization catalyst, with the water subsequently being removed by evaporation. Thermoset compositions are prepared by heating the curable prepregs for a time and at a temperature sufficient to effect free radical polymerization and crosslinking of the water-soluble composition. Water-base compositions containing pigments are useful as thermosetting paints, chiefly for metal surfaces, and may be thermoset in the same way.