We investigate whether 8-month-old infants can detect prosodic cues relevant in sentence structuring. We recorded event-related potentials to examine online responses to the processing of prosodic boundaries. Prior studies in adults have validated the closure positive shift as reflecting prosodic boundary perception during speech processing. The current study shows that in the event-related potentials of 8-month-olds, a closure positive shift is elicited in relation to the prosodic boundaries in speech, suggesting that these infants are able to structure speech input into prosodic units on a neurophysiological basis similar to that seen in adults. A delay in latency of the infant closure positive shift, however, suggests that children's exploitation of prosodic boundaries for the segmentation of the speech stream is still developing.