Living polymerization of styrene was observed using gamma radiation as a source of initiation and 1-phenylethyl phenyldithioacetate as a reversible addition-fragmentation chain transfer (RAFT) agent. The gamma radiation had little or no detrimental effect on the RAFT agent, with the molecular weight of the polymer increasing linearly with conversion (up to the maximum measured conversions of 30%). The polymerization had kinetics (polym.) consistent with those of a living polymerization (first order in monomer) and proportional to the square root of the radiation-dose rate. This initiation technique may facilitate the grafting of narrow polydispersity, well-defined polymers onto existing polymer surfaces as well as allow a wealth of kinetic experiments using the constant radical flux generated by gamma radiation.