A process for preparing vinyl chloride based polymers by suspension polymerization provides granular products characterized by improved uniformity of particle size, high porosity and rapid fushion rates. Pre-emulsification of vinyl chloride in the presence of a polyvalent metal ion, a surface active agent and a ''''seed'''' polymer, subsequently polymerized by the after-addition of initiator offers a high degree of control over physical properties of the resulting polymer that are also consistently reproducible. By addition of surfactants during the course of polymerization stability is improved. The combination of pre-emulsification, delayed initiation and post addition of surfactant substantially eliminates reactor wall fouling and crust formation.