Polymerizations of methyl methacrylate (MMA) in ternary oil-in-water microemulsions using the cationic surfactants stearyltrimethylammonium chloride (STAC), cetyltrimethylammonium bromide (CTAB), or a mixture of nonionic nonylphenoxy poly(ethylene glycol) surfactants produce latex particles having weight average diameters of 17-41 nm. The small particle sizes and high molecular weights (M-W = (2.5-6.5) x 10(6)) indicate that most samples consist mainly of particles containing one polymer chain. The particle size varies little when the surfactant to monomer weight ratio is greater than or equal to 1. Polymerizations using STAC at 35 degrees C produce smaller particles than at 60 degrees C. Radical polymerization of MMA in microemulsions produces predominantly syndiotactic PMMA containing 58-61% rr triads at 60 degrees C and 63-65% rr triads at 35 degrees C. The high molecular weight PMMA samples have T-g= 125-126 degrees C.