The accurate perception of time intervals in the 10–100-ms range plays an important role in sensory encoding, including the processing of speech, yet little is known about the development of this ability, particularly during adolescence. Here, auditory temporal-interval discrimination thresholds were measured in normally developing individuals aged 11 (n=14), 14 (n=8), and 18–26 (n=17) years. Both average performance (mean within-listener threshold) and performance consistency (within-listener standard deviation) were evaluated for each listener with a 100-ms standard at each of two frequencies, 1 and 4 kHz. At the group level, for both frequencies, average performance improved significantly, from ∼48 to ∼22 ms, between 11 and 14 years of age (both p≤0.02), but did not improve further between 14 years and adulthood (both p≥0.92). There were parallel improvements in performance consistency. At the individual level, while the majority of 11-year-olds showed poorer performance than 14-year-olds and adults on both measures, a sizable minority performed within the range of adults. Thus it appears that, both in terms of average performance and performance consistency, the sensitivity to differences in temporal intervals has a developmental time course that can differ considerably across individuals, but, for most, reaches well into adolescence. [Work supported by NIH/NIDCD.]