The present invention provides an economical route to environmentally friendly polymeric coatings with a high content of raw materials from renewable resources. These polymeric coatings offer performance characteristics that are competitive with conventional coating systems. The unique polymers on which this invention is based are copolymers of triglyceride oils, such as soybean oil, linseed oil, or another natural oil, with a vinyl compound, such as an acrylate or methacrylate, or a vinyl aromatic monomer. The present invention more specifically discloses a water dispersible, self-crosslinkable prepolymer composition which is comprised of a triglyceride oil having appended thereto (1) hydroxyl groups, (2) epoxy groups, (3) moieties which contain at least one aldehyde group or at least one ketone group, and (4) moieties which contain at least one vinyl and/or substituted vinyl group. In one embodiment of this invention the moiety which contains at least one vinyl group is derived from maleic anhydride.