The dispersion polymerization of styrene in an ethanol-water mixture using polystyrene-b-poly(ethylene oxide) macromonomers as stabilizers has been investigated. The influence of parameters such as the nature of the polymerizable group, the hydrophilic/hydrophobic balance, the overall molar mass, and the molecular architecture of the macromonomers on the colloidal dispersion has indeed been studied. Macromonomers of rather low molar mass and exhibiting high critical micellar concentration were best suited to produce stable particles. Latex particles of rather narrow size distribution could be obtained in the range of 300-350 nm with styrenyl or maleate ended PS-b-PEO macromonomers.