The article by Guillaume Thierry is a welcome one, alerting the field to the exciting ways in which event-related potentials (ERPs) can be used to study cognitive development. It is also timely: there is great interest in the brain sciences, and in how neuroscience can be applied to cognitive development and indeed to education. In my view, however, the article is perhaps too cautious. It does not seem necessary to delay the use of ERPs in cognitive work until all in the field have agreed on the sound characterization of ERP components. It should be possible for further characterization to proceed hand-in-hand with data gathering on applied questions. In fact, as partly noted by Thierry, in the auditory domain well-characterized ERP components are already available, even for infants (e.g. Cheour et al., 1997; Leppänen and Lyytinen, 1997). Furthermore, it is of developmental interest to study older children as well as infants. If ERPs are seen as a tool to complement existing behavioural investigations, rather than as a stand-alone method to be used independently, then auditory ERPs can certainly be used in current cognitive-developmental work. Copyright © 2005 John Wiley & Sons, Ltd.