The anionic polymerization of methyl methacrylate in toluene at -78 degrees C with lithium amides of various secondary amines (diisopropylamine, N-isopropylaniline, N-n-butylaniline, indoline, and N-ethyl-o-toluidine) as initiators was studied. The tacticity of the resulting poly(methyl methacrylate)s (PMMAs) was dependent on the kind of secondary amine, and highly isotactic PMMAs (91-93% mm) were obtained when lithium amides of N-isopropylaniline and N-n-butylaniline were employed. The isotacticity of the PMMAs further increased up to 98% mm with initiating systems composed of the lithium amides, n-butyllithium, and transition-metal halides (WCl6, MoCl5, and NbCl5). (c) 2005 Wiley Periodicals, Inc.