The facile and efficient one-pot synthesis of monodisperse, highly crosslinked, and living functional copolymer microspheres by the ambient temperature iniferter-induced living radical precipitation polymerization (ILRPP) is described for the first time. The simple introduction of iniferter-induced living radical polymerization (ILRP) mechanism into precipitation polymerization system, together with the use of ethanol solvent, allows the direct generation of such uniform functional copolymer microspheres. The polymerization parameters (including monomer loading, iniferter concentration, molar ratio of crosslinker to monovinyl comonomer, and polymerization time and scale) showed much influence on the morphologies of the resulting copolymer microspheres, thus permitting the convenient tailoring of the particle sizes by easily tuning the reaction conditions. In particular, monodisperse poly(4-vinylpyridine-co-ethylene glycol dimethacrylate) microspheres were prepared by the ambient temperature ILRPP even at a high monomer loading of 18 vol %. The general applicability of the ambient temperature ILRPP was confirmed by the preparation of uniform copolymer microspheres with incorporated glycidyl methacrylate. Moreover, the livingness of the resulting polymer microspheres was verified by their direct grafting of hydrophilic polymer brushes via surface-initiated ILRP. Furthermore, a grafting from particle growth mechanism was proposed for ILRPP, which is considerably different from the grafting to particle growth mechanism in the traditional precipitation polymerization. (c) 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013, 51, 1983-1998