Epoxystyrene (ethenylphenyloxirane) has been synthesised in a single-stage process by mono-epoxidation of divinylbenzene using magnesium monoperoxyphthalic acid. Copolymers of epoxystyrene and styrene were then synthesised by living free radical polymerisation and atom transfer radical polymerisation methods. In both cases the oxirane group of epoxystyrene was found to be stable under the conditions of polymerisation, though at the temperatures required for LFRP, copolymers with bimodal molecular weight distributions resulted. In contrast, as long as the temperature used for ATRP was kept below 100 degrees C, copolymers with narrow, monomodal distributions could be obtained.