Paul Yoder, Ph. D., is a Professor of Special Education, Peabody College, Vanderbilt University and an Investigator at Vanderbilt Kennedy Center, Vanderbilt University. He has been studying the relative efficacy of language interventions for over 23 years. Much of this work has attempted to identify which aspects of children we should use to select among treatment options. Preschoolers with SLI are very heterogeneous. They do not all respond to a particular treatment method. If we could identify the child characteristics on which they vary that also affect treatment uptake, we could probably do a better job of matching the treatment method to the child's abilities and disabilities. One candidate for such a child characteristic is typicality of speech processing. In the last 10 years, Yoder has been using event related potential (ERPs) to attempt to measure speech differentiation. In his experience, behavioral measures of speech differentiation are insufficiently sensitive to the types of individual differences in preschoolers with disabilities that predict differential response to grammatical treatment methods. Only in the last year has he been convinced that ERPs hold great promise for helping us select among grammatical treatment options for preschoolers with SLI.