The polymerization of methyl methacrylate and various acrylates initiated by ester enolates in the presence of cesium halide-trialkylaluminum complexes, Cs[AlnR2nX] (n = 1, 2; R = Et, Bu-i), in toluene has living and controlled character at -20 degreesC for methacrylates (X = Cl) and at -65 degreesC for n-butyl acrylate (X = F). Quantitative monomer conversions are usually reached, leading to polymers with narrow molecular weight distributions (M-w/M-n < 1.1). Kinetic investigations indicate a rather complex polymerization mechanism, and we assume an equilibrium between at least two active species. With this new initiating system, beside acrylate homopolymers, random and graft copolymers can be synthesized.