The ring-opening metathesis polymerization (ROMP) of enantiomerically pure 2-substituted norbornenes carried out with Mo(CH-t-Bu)(NAr)(O-t-Bu)2 in chlorobenzene or with K2[RuCl5(H2O)] in aqueous solvents leads to polymers that show optical activity. The increasing specific rotations of the polymers from acetate to butyrate to benzoate with both catalysts is explained by increasing substituent group size.