Polymerizations of methyl methacrylate with (α-diimine)nickel(II)/methylaluminoxane (MAO) and (pyridyl bis(imine))iron(II) and (pyridyl bis(imine))cobalt(II)/MAO are reported. Effects of structural variation of the ligand on the activities of catalysts and polymer microstructure are described. The catalyst systems gave syndiorich poly(methyl methacrylate). The α-diimine system showed much higher activity than the pyridyl bis(imine) systems under similar polymerization conditions.