Metal-free controlled ring-opening polymerization of glycidyl phenyl ether (GPE) was achieved using tetra-n-butylammonium fluoride (Bu(4)NF) as an initiator in the presence of water and ethanol as chain transfer agents (CTAs). Number-averaged molecular weight of poly(GPE) increased with an increase of [GPE](0)/([Bu(4)NF](0) + [CTA](0)) values, showing relatively narrow molecular-weight distributions. NMR spectroscopic analysis exhibited a formation of ethoxy groups as well as FCH(2) at the initiating poly-mer chain-end when ethanol was used as the CTA in the polymerization. These results indicate that Bu(4)NF acts as a catalyst as well as the initiator for this polymerization system. (C) 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 49: 5210-5216, 2011