A new grafting-from procedure was developed for the synthesis of arborescent styrene polymers of successive generations in a single reaction pot. Styrene was first copolymerized anionically in a semibatch process with 1,3-diisopropenylbenzene (DIB), and the chains were terminated with methanol. The pendent isopropenyl moieties of the DIB units were then reacted with sec-butyllithium to generate a polyfunctional anionic macroinitiator. Further additions of styrene-DIB monomer mixture to the activated linear substrate yielded a comb-branched (generation GO) copolymer. After termination of the chain ends and activation of the double bonds on the GO Substrate, styrene monomer was added to generate G I arborescent polystyrenes, with a dendritic architecture. Alternately, the GO copolymer was isolated by precipitation and activated in a separate procedure. The size (molecular weight) of the side chains in the G1 polymer was conveniently controlled by varying the amount of monomer added to the GO macroinitiator. The reaction conditions were optimized to obtain graft polymers with relatively low polydispersity indices (M-w/M-n = 1.1 - 1.3) and absolute weight-average molecular weights M-w reaching 7 x 10(6). The intrinsic viscosity in toluene of the arborescent G1 polystyrenes synthesized was up to 7.2 times lower than for linear polystyrene samples of comparable molecular weight.