Only trace amts. of Bu4NCN were necessary to catalyze rapid group-transfer polymn. of Me methacrylate (I) in THF in the presence of (1-methoxy-2-methyl-1-propenyloxy)trimethlysilane (II). Under group-transfer polymn. conditions, its initiation of anionic polymn. of I could be ignored as well as its oligomerization of II. Group transfer polymn. of I in the presence of Bu4NCN and II was compared to polymn. using difluorides such as tris(piperidino)sulfonium bifluoride or tris(dimethylamino)sulfonium difluorotrimethylsilicate. The effects of the catalysts on the rate of polymn. and the conversion were discussed, and problems encountered using the difluorides were discussed with respect to the advantages of the Bu4NCN system.