Bifunctional initiators [Me(R)C:C(OMe)OSiMe3; R = vinyl, allyl, isoprenyl; and p-CH2:CHC6H4CH:C(OMe)OSiMe3] were prepd. for group-transfer polymn. (GTP). All initiators initiated GTP of Me methacrylate in THF with tris(piperidino)sulfonium bifluoride or Bu4NCN as catalysts to yield macromonomers with low polydispersities. GTP should be performed as the first step, since the silyl groups of the initiators underwent side reactions with active species of other polymn. systems. Macromonomers from isoprenyl- or 4-vinylphenyl-substituted initiators could be radically copolymd. with styrene to yield graft copolymers.