Chirality can be used as a design tool to control the mechanical rigidity of hydrogels formed from self-assembling peptides. Hydrogels prepared from enantiomeric mixtures of self-assembling beta-hairpins show nonadditive, synergistic, enhancement in material rigidity compared to gels prepared from either pure enantiomer, with the racemic hydrogel showing the greatest effect. CD spectroscopy, TEM, and AFM indicate that this enhancement is defined by nanoscale interactions between enantiomers in the self-assembled state.