Abstract: This invention relates to novel rosin-fatty acid vinylic polymer compositions and the process for preparing them. In particular, the invention relates to novel rosin-fatty acid vinylic polymer compositions that exhibit properties which make them useful as components of paper sizes, as components of coatings, and as support resins for producing polymer latices that can be employed in formulating water-based coatings and inks. More particularly, these rosin-fatty acid vinylic polymer compositions are mixtures that are produced by the addition polymerization reaction of vinylic monomers in the presence of saturated fatty acids, hydrogenated dimer acids, hydrogenated rosins, or mixtures thereof.