Processing of auditory information in the cortex continues to develop into later childhood and adolescence. Recent research has indicated that intraclass correlation (ICC) is the best method for capturing maturation in auditory event-related potentials (AEPs) of school-age children. However, the sensitivity of the ICC approach in discerning AEP changes in children has not been consistently demonstrated and positive results have not been replicated. We attempted this replication and further explored whether AEP maturation estimated using the ICC approach predicts cognitive and linguistic abilities in addition to chronological age. We measured AEPs in response to simple tones in groups of 7-, 8-, 9- and 10-year olds with typical development (N = 67) and used ICC to estimate the age equivalent of each child's AEP (AEP-age). Results indicated that ICC differentiated 7- to 8-year-old children from 9- to 10-year-old children and that AEP-age predicted both chronological age and significant, unique variance in language ability, but not in nonverbal IQ. Our findings support the view that auditory organization in children reflects both general developmental maturation and more specific development of language skills, and support the future use of AEP-age to identify and understand individual differences in brain maturation in typically developing and clinical populations.