Purpose: Children and early adolescents seem to have an advantage over adults in acquiring nonnative speech sounds, supported by evidence showing that earlier age of acquisition strongly predicts second language attainment. Although many factors influence children's ultimate success in language learning, it is unknown whether children rely on different, perhaps more efficient learning mechanisms than adults. Method: The current study compared children (aged 10-- 16 years) and adults in their learning of a nonnative Hindi contrast. We tested the hypothesis that younger participants would show superior baseline discriminability or learning of the contrast, better memory for new sounds after a delay, or improved generalization to a new talker's voice. Measures of phonological and auditory skills were collected to determine whether individual variability in these skills predicts nonnative speech sound learning and whether these potential relationships differ between adults and children. Results: Adults showed superior pretraining sensitivity to the contrast compared to children, and these pretraining discrimination scores predicted learning and retention. Even though adults seemed to have an initial advantage in learning, children improved after a period of off-line consolidation on the trained identification task and began to catch up to adults after an overnight delay. Additionally, perceptual skills that predicted speech sound learning differed between adults and children, suggesting they rely on different learning mechanisms. Conclusions: These findings challenge the view that children are simply better speech sound learners than adults and suggest that their advantages may be due to different learning mechanisms or better retention of nonnative contrasts over the broader language learning trajectory.