Recent studies have shown that infants predict the outcome of moving objects in complex events from visual information. Typically, infants see the surfaces and obstacles that the object will encounter and part of the action sequence itself. The purpose of this research is to explore whether infants can also use auditory cues to interpret physical events. The research will focus on two questions: (1) Can a moving object be localized by auditory cues alone? (2) Can the appearance of an object be anticipated by auditory cues? The goal of the planning activities is to develop and pilot test events in which auditory cues specify the movement or appearance of an object. Infants' reaching behavior in the dark will index their prediction of the location and availability of the object. Infants at 6.5 and 8.5 months of age will participate in the pilot studies. Events to be tested include a ball falling down stairs, a sounding object rotating on a turntable, and the operation of a jack-in-the-box toy. The first two events will emphasize localization, while the last event will explore the signalling function of sound. Evidence that infants can reason about events from auditory cues would support theories of cognitive development that posit early or even innate knowledge about the behavior of objects in the world. Further, methodologies that document infant cognition can provide diagnostic tools for early detection of cognitive deficits.