The photopolymerization of styrene with a well-defined molecular architecture and a low polydispersity index and with methyl and phenylseleno (-SePh) groups at alpha- and omega-chain ends, respectively, was performed via a controlled/living radical polymerization with a new initiating system, 1-(phenylseleno)ethyl benzene/tert-butyl diphenyl (phenylseleno) silane, through the absorption of visible light at room temperature. A novel initiating living radical polymerization was examined. The yield and number-average molecular weight (M-n) of the resulting polymer increased with the reaction time. Furthermore, a linear relationship was found in a plot of M-n versus the polymer yield. These results indicated that this polymerization proceeded through a living radical mechanism. (C) 2004 Wiley Periodicals, Inc.