Languages differ in the importance of acoustic dimensions for speech categorization. This poses a potential challenge for second language (L2) learners, and the extent to which adult L2 learners can acquire new perceptual strategies for speech categorization remains unclear. This study investigated the effects of extensive English L2 immersion on speech perception strategies and dimension-selective-attention ability in native Mandarin speakers. Experienced first language (L1) Mandarin speakers (length of U.K. residence > 3 years) demonstrated more native-like weighting of cues to L2 suprasegmental categorization relative to inexperienced Mandarin speakers (length of residence < 1 year), weighting duration more highly. However, both the experienced and the inexperienced Mandarin speakers continued to weight duration less highly and pitch more highly during musical beat categorization and struggled to ignore pitch and selectively attend to amplitude in speech, relative to native English speakers. These results suggest that adult L2 experience can lead to retuning of perceptual strategies in specific contexts, but global acoustic salience is more resistant to change.