Abstract: Stable dispersions of halogen-containing addition polymers, such as polyvinylidene fluoride, in water-dilutable liquid media, for example 2-butoxyethanol, are produced by dispersing pre-formed particles of the polymer, of a number-average size in the range 0.1-10 microns, in the liquid medium in the presence of a polymeric dispersant containing in the molecule a hydrophobic polymer chain and strongly ionized groups, in particular quaternary ammonium groups, the strongly ionized groups being present in such a proportion as to provide a charge density of from 0.05 to 6.0 milliequivalents per gram of the total dispersant. The dispersions thus obtained are valuable as a basis for water-borne coating compositions.