The auditory frequency resolving ability of preschool children, school-aged children, and adults was assessed in a standard forced-choice masking experiment. Thresholds for pure-tone signals at 500 Hz, 2000 Hz, and 4000 Hz were obtained in two masking conditions. In one condition, the masker was a 4000-Hz-wide band of noise centered at the signal frequency; in the other, there was a notch in the noise spectrum, approximately one-half octave wide and 50 dB deep, centered at the signal frequency. Frequency resolving ability was inferred from the difference in signal threshold between the two masking conditions. The adaptive forced-choice psychophysical procedure was embedded in a video game in order to obtain rigorous psychophysical data within the attentional limits of young children. This procedure produced data from children as young as 3 years old that were qualitatively indistinguishable from adult data. However, the threshold estimates from the children were more variable from run to run than were the estimates obtained from adults. The mean data from this experiment suggest that frequency resolving ability improves at all frequencies with increasing age.