AbstractThe catalytic amount of inorganic bases (i.e., NaOH, Na3PO4, NaHCO3, and Na2CO3) and organic bases such as pyridine and triethylamine was used as the additives in an iron‐mediated atom transfer radical polymerization with activators generated by electron transfer (AGET ATRP) of a polar monomer methyl methacrylate (MMA) using FeCl3·6H2O as the catalyst, ethyl 2‐bromoisobutyrate (EBiB) as the initiator, ascorbic acid (AsAc) as the reducing agent, and tetrabutylammonium bromide (TBABr) as the ligand. All these bases can result in dual enhancement of polymerization rate and controllability over molecular weight while keeping low Mw/Mn values (<1.3) for the resultant polymers. For example, the polymerization rate of AGET ATRP with a molar ratio of [MMA]0/[EBiB]0/[FeCl3·6H2O]0/[TBABr]0/[AsAc]0/[NaOH]0 = 500/1/1/2/2/1.5 using NaOH as the additives was more than two times of that without NaOH. The nature of “living”/controlled free radical polymerization in the presence of base was confirmed by chain‐extension experiments. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011