El Niño is an anomalous condition that historically has been studied in the coastal region of the eastern tropical South Pacific. The phenomenon is commonly characterized there by the rapid appearance of anomalously high sea level and sea surface temperatures, and southward transport of the warmer, fresher equatorial waters. Observational evidence also suggests that El Niño is associated with a large-scale weakening of the equatorial wind systems over a large extent of the ocean interior. The problem investigated here is whether these ocean and atmosphere events are dynamically connected. A model is used to follow the initial baroclinic response of the eastern Pacific Ocean to different distributions of interior wind stress change. Model results suggest the following conclusions. Changes in the meridional wind field cannot cause an El Niño event. Changes in the zonal wind field outside of the equatorial band (roughly ±5° of latitude) are not important in generating El Niño. A symmetric weakening ... Abstract El Niño is an anomalous condition that historically has been studied in the coastal region of the eastern tropical South Pacific. The phenomenon is commonly characterized there by the rapid appearance of anomalously high sea level and sea surface temperatures, and southward transport of the warmer, fresher equatorial waters. Observational evidence also suggests that El Niño is associated with a large-scale weakening of the equatorial wind systems over a large extent of the ocean interior. The problem investigated here is whether these ocean and atmosphere events are dynamically connected. A model is used to follow the initial baroclinic response of the eastern Pacific Ocean to different distributions of interior wind stress change. Model results suggest the following conclusions. Changes in the meridional wind field cannot cause an El Niño event. Changes in the zonal wind field outside of the equatorial band (roughly ±5° of latitude) are not important in generating El Niño. A symmetric weakening ...