Reference data for the acoustic vowel space area (VSA) in children and adolescents do not currently appear to be available in a form suitable for normative comparisons. In the current study, individual speaker formant data for the four corner vowels of American English (/i, u, ae, [alpha]/) were used to compute individual speaker VSAs. The sample included 300 children aged 5-18 years and 38 adults aged 25-50 years. Age trends and sex differences were examined and reference data for clinical application were developed. Findings indicated significant declines in VSA with age; sex differences were not fully apparent until late adolescence and adulthood. Implications are discussed. (Contains 2 tables and 1 figure.)