Activators regenerated by electron transfer atom transfer radical polymerization (ARGET ATRP) conditions utilizing a low concentration of catalyst are successfully applied for the preparation of well-defined poly(glycidyl methacrylate) without the addition of external reducing agents. The living character of polymerization is evidenced by successful chain extensions with methyl methacrylate and methyl acrylate, again, in the absence of additional reducing agents, yielding block copolymers. The epoxide groups in glycidyl methacrylate or the corresponding polymer can serve as an intrinsic reducing agent to continuously regenerate the Cu-I-based ATRP activator from the Cu-II halide complex present in the systems. The reactivity of various epoxides in the reduction of the (CuBr2)-Br-II complex of tris(2-pyridylmethyl)amine is compared.