Abstract: Polyvinyl chloride and polyvinyl chloride containing up to 20 percent of a comonomer can be obtained in the form of small particle size spherical glassy surface particles by a process of bulk polymerization of monomer or monomers comprising two stage polymerization wherein high shear agitation is used during the first stage and low shear agitation is used in the second stage. To obtain a reduction in particle size, the polymerization in the first stage is conducted in contact with at least one of (A) an additive comprising an organic or inorganic, inert, fine particle size material solid at least at reaction temperatures, and insoluble in said monomer or monomers used, and (B) a cationic, anionic, or non-ionic surface active agent. A portion of the polymerization in a second stage reaction is conducted at temperature and pressure sufficient to render the surface of the individual particles or agglomerates glassy and fused.