Polymerization of isocyanopeptides results in the formation of high molecular mass polymers that fold in a proteinlike fashion to give helical strands in which the peptide chains are arranged in ß-sheets. The ß-helical polymers retain their structure in water and unfold in a cooperative process at elevated temperatures. The peptide architecture in these polymers is a different form of the ß-helix motif found in proteins. Unlike their natural counterparts, which contain arrays of large -sheets stacked in a helical fashion, the isocyanopeptide polymers have a central helical core that acts as a director for the ß-sheet-like arrangement of the peptide side arms. The helical structure of these isocyanopeptide polymers has the potential to be controlled through tailoring of the side branches and the hydrogen-bonding network present in the ß-sheets.