The homopolymerization of 2-(2-bromopropionyl)oxy)ethyl acrylate (BPEA) by atom transfer radical polymerization (ATRP), a "living"/controlled radical polymerization system, has yielded a hyperbranched polymer. Variation of the reaction conditions and especially the concentration of copper(II) in the polymerization system affects not only the rate of polymerization but also the chain architecture. The copper(II) concentration in the polymerization medium is affected by solvent, the ligand used to complex copper, and temperature. The effects of temperature and ligand on the polymerization rate and the resulting chain architecture were studied.