This study investigates whether adult L2 learners’ experience with lexical tones and pitch accent in their first language facilitates the acquisition of L2 lexical tones. Three groups of beginning learners of Mandarin with different L1 prosodic experience: native Hmong (a tone language), native Japanese (a pitch and accent language), and native English (a non-tone, non-pitch accent language) speakers participated as listeners in a perception test on the four Mandarin tones. Results showed that native English listeners performed equally well as native Japanese listeners but native Hmong speakers performed significantly worse than the native Japanese and native English speakers in perceptual accuracy of Mandarin tones. The findings suggest that experience with lexical tones and pitch accent may not always facilitate learning. The lack of exact mapping of L2 tones onto L1 tones may interfere with the acquisition of nonnative tones especially at the initial stage of learning.