By contrast to traditional free radical emulsion polymerization, catalytic polymerization allows for polymer microstructure control. In terms of monomers polymerizable, both techniques are largely complementary. Since the beginning of this decade, an increasing number of reports on polyolefin, polybutadiene, polyalkenamer, polynorbornene, polyketone and polyacetylene dispersions prepared by catalytic polymerization in disperse aqueous systems has appeared. This contribution reviews the preparation of these dispersions, their colloidal properties, particle formation mechanisms, particle morphologies and polymer microstructures.