AbstractThe living polymerization of methyl methacrylate with aluminium porphyrin (1) proceeded dramatically rapidly at room temperature in the presence of sterically crowded organoaluminium compounds such as methylaluminiumortho‐substituted diphenolates (3a − 3g), bis(triphenylmethanolate) (4a), and triphenylaluminium, where undesired reaction between the growing species and the Lewis acids was sterically suppressed. On the basis of this Lewis acid ‐ assisted high‐speed living polymerization, various monomers such as ethyl, propyl, butyl, and dodecyl methacrylates, methacrylonitrile, and 1,2‐epoxypropane were polymerized very rapidly with the aluminium porphyrin ‐ Lewis a