Longitudinal measures of peak-compensated static acoustic admittance and tympanometric width are reported for infants and toddlers from 6 months to 30 months of age, based on over 1600 assessments of 88 children during a 24-month period. The subjects were all African-American children in full-time day care. Significant age effects were observed, with younger children displaying lower static admittance values and wider tympanograms. The results of this investigation underscore the importance of age- and population-specific norms when using acoustic admittance measures to evaluate middle ear status in children.