To test the validity of a new computerized task to assess children's receptive vocabulary, event-related potentials (ERPs) were recorded from 56 typically developing children ranging in age from 5 to 12 years. This ERP-computerized vocabulary task does not require a child to give a verbal or motor (i.e. pointing) response. Single pictures, from an existing standardized test of receptive vocabulary, were presented on a computer screen and simultaneously named either correctly (congruent) or incorrectly (incongruent) via a computer. As predicted, the N400 amplitude was found to be significantly higher to the incongruent picture–word pair (i.e. the child knew it was an incorrect pairing) than to the congruent picture–word pair (i.e. the child knew it was a correct pairing). This effect was found for each of the four age groups (5 to 6 years, 7 to 8 years, 9 to 10 years, 11 to 12 years). This task accurately estimated current receptive vocabulary in typically developing children. Although still in the development stage, it may eventually serve as an adjunct to a thorough neurological and neurodevelopmental assessment of some children presenting with moderate to severe cerebral palsy.