Despite the widespread exploration of alpha-peptides as catalysts, there are few examples of beta-peptides that alter the course of a chemical transformation. Our previous work demonstrated that a special class of beta(3)-peptides spontaneously self-assembles in water into discrete protein-like bundles possessing unique quaternary structures and exceptional thermodynamic stability. Here we describe a series of beta(3)-peptide bundles capable of both substrate binding and chemical catalysis-ester hydrolysis. A combination of kinetic and high-resolution structural analysis suggests an active site triad composed of residues from at least two strands of the octameric bundle structure.