We report enantioselective epoxidation reactions that are catalyzed by aspartic acid-containing peptides. The strategy involves the transient conversion of the aspartate carboxylic acid side chain to the corresponding peracid. Reaction of olefin with the activated catalyst regenerates that catalyst, which may be subjected to multiple turnovers through a carbodiimide-mediated dehydration pathway. Enantioselectivities of up to 92% ee are observed for a class of urethane-substituted olefins.