Psychophysical research in adults has defined a temporal window for binding auditory and visual stimuli into a unified perceptual construct. In an effort to gain insight into the neurophysiological correlates of this multisensory temporal binding window, perceptual reports and cortical event related potentials (ERPs) were collected in adults during a simultaneity judgment task. Objectively synchronous and asynchronous visual and auditory stimuli were presented in a randomly interleaved fashion and subjects were asked to report on their perception of simultaneity. In the asynchronous conditions, the onset of the visual stimulus preceded the onset of the auditory stimulus in 100 ms steps. Examination of perceptual responses revealed that the probability of reporting the stimuli as synchronous decreased rapidly across visual-auditory delays of 100 to 300 ms. Analysis of the auditory P1, N1, P2 complex relative to the tone pip revealed differences in the amplitude of responses to the veridical simultaneous condition relative to asynchronous conditions, and suggest a relationship between the perceptual binding of the multisensory stimuli and ERP responses. Ongoing work seeks to further elucidate the components of this ERP complex, and will focus on correlating the perceptual and physiological data in both the amplitude and latency domains.