The simultaneous control of the molecular weights and the tacticity was attained even during radical polymerization by the judicious combinations of the living/controlled radical polymerizations based on the fast interconversion between the dormant and active species, and the stereospecific radical polymerizations mediated by the added Lewis acids or polar solventsvia the coordination to the monomer/polymer terminal substituents. This can be useful for various monomers including not only conjugated monomers, such as acrylamides and methacrylates, but also nonconjugated ones such as vinyl acetate and N-vinylpyrrolidone. Stereoblock polymers were easily obtained by the addition of the Lewis acids or by change of the solvents during the living radical Polymerizations. (c) 2006 Wiley Periodicals, Inc.