Here we present a high-resolution marine sediment record from the El Ni¿o region off the coast of Peru spanning the last 20,000 years. Sea surface temperature, photosynthetic pigments, and a lithic proxy for El Ni¿o flood events on the continent are used as paleo--El Ni¿o--Southern Oscillation proxy data. The onset of stronger El Ni¿o activity in Peru started around 17,000 calibrated years before the present, which is later than modeling experiments show but contemporaneous with the Heinrich event 1. Maximum El Ni¿o activity occurred during the early and late Holocene, especially during the second and third millennium B.P. The recurrence period of very strong El Ni¿o events is 60--80 years. El Ni¿o events were weak before and during the beginning of the Younger Dryas, during the middle of the Holocene, and during medieval times. The strength of El Ni¿o flood events during the last millennium has positive and negative relationships to global and Northern Hemisphere temperature reconstructions.