Vinylbenzyl-terminated polystyrene (PS) macromonomers were prepared by the direct reaction of living PS anions withp-chloro-methylstyrene (CMS). The propagation rate constant (kp) was obtained from free-radical polymerization of PS macromonomers in the presence of 1-buten-3-ol as a degradative chain transfer agent by using gel permeation chromatography (GPC) analysis. In this condition, the polymer radicals were terminated by a unimoiecular mechanism. Subsequently, we studied the radical propagation step of vinylbenzyl-terminated diblock poly[styrene (S)-b-isoprene (I)] and poly[S-b-2-vinylpyridine (2VP)] macromonomers in benzene. The vinylbenzyl groups at the terminal ends of diblock macromonomers apparently take the concentrated state in micelles. These results are discussed from the point of view of polymer-polymer reactions.