Empirical investigation of the degree to which testing predicts children's real-world functioning following traumatic brain injury (TBI) is sparse. This article reviews the research in neuropsychology, which offers only moderate correlations between test scores and everyday functioning. This line of research is hindered by several methodological issues: difficulty translating performance on standardized testing into real-world capacities, measurement of real-world functioning, developmental factors, and the influence of intervening variables in the natural environment. Ecologically valid assessment may require multiple data sources. More research is needed to respond effectively to questions about children's everyday functioning after traumatic brain injury.