Amphiphilic heteroarm star copolymers bearing polystyrene (PS) and poly(ethylene oxide) (PEG) branches have been synthesized by sequential anionic ’living’ copolymerization. These samples have been characterized adequately and shown to exhibit rather well-defined structures. The functionality of the stars is influenced mainly by the molar ratio of divinylbenzene per living ends and the molecular weight of the linear PS tetrahydrofuran, which is not a selective solvent for the different arms. Finally, it has been shown that the PEO arms can be crystallized, forming well-defined spherulites. This ability is strongly affected by the PEO content and the thermal history of the samples.