A general methodology for the synthesis of star polymers with large number of polypeptide arms is described. The synthesis is based on the arm-first step-growth polymerization of bifunctional macromonomers by coppercatalyzed azide-alkyne cycloaddition. Star polymers with up to 18 poly-gamma-benzyl-L-glutamate (PBLG) arms have been synthesized and characterized. It is shown that the preferred secondary structure of PBLG is significantly affected by the degree of chain packing/crowding.