The living radical polymerization of styrene in bulk was successfully performed with a tetraethylthiuram disulfide/copper bromide/2,2 ' -bipyridine (bpy) initiating system. The initiator Et,NCS,Br and the catalyst cuprous bromide (CuBr) were produced from the reactants in the system through in situ atom transfer radical polymerization ATRP). A plot of natural logarithm of the ratio of original monomer concentration to monomer concentration at present, ln([M](0)/[M]) versus time gave a straight line, indicating that the kinetics was first-order. The number-average molecular weight from gel permeation chromatography (GPC) of obtained polystyrenes did not agree well with the calculated number-average molecular weight but did correspond to a 0.5 initiator efficiency. The polydispersity index (i.e., the weight-average molecular weight divided by the number-average molecular weight) of obtained polymers was as low as 1.30. The resulting polystyrene with a-diethyldithiocarbamate and W-Br end groups could initiate methyl methacrylate polymerization in the presence of CuBr/bpy or cuprous chloride/bpy complex catalyst through a conventional ATRP process. The block polymer was characterized with GPC, H-1 NMR, and differential scanning calorimetry.