The controlled nitroxide-mediated copolymerization of glycidyl methacrylate (GMA) and styrene (S) with varying GMA molar feed fractions (fGMA,0 = 0.12-0.94) was accomplished by using a SG1-based alkoxyamine initiator bearing a N-succinimidyl ester group (NHS-BlocBuilder) in 50 wt% 1,4-dioxane solution at 90 [degree]C. Copolymerizations indicated linear evolution of number average molecular weight Mn with respect to conversion up to approximately 50% and narrow molecular weight distributions with Mw/Mn = 1.22-1.44 and GMA incorporation into copolymer (FGMA) as high as 0.92. No additional SG1 free nitroxide was required to control polymerizations, even at high fGMA,0. Chain extensions of poly(GMA-ran-S) macroinitiators with S at 110 [degree]C yielded a high fraction of block copolymer in most cases (except at the highest FGMA), as clear, monomodal shifts in Mn using gel permeation chromatography (GPC) were observed, thereby suggesting the poly(GMA-ran-S) macroinitiators were substantially living.