Purpose: This research compared individuals from two first language (L1) backgrounds (English and Japanese) to determine how they may differ in their perception of Mandarin tones (Tones 1 vs. 2 [T1-T2], Tones 1 vs. 3 [T1-T3], Tones 1 vs. 4 [T1-T4], Tones 2 vs. 3 [T2-T3], Tones 2 vs. 4 [T2-T4], Tones 3 vs. 4 [T3-T4]) on account of their L1. Method: The participants included two groups of "learners of Mandarin" (23 English speakers, 18 Japanese speakers), two groups of "nonlearners of Mandarin" (24 English speakers, 21 Japanese speakers), and a "control group" of 10 Mandarin speakers. A four-alternative forced-choice discrimination task that included 360 trials was presented in three blocks of 120 trials. Results: The native Mandarin group was more accurate in their tonal discrimination of all six tone pairs than all the nonnative groups. While Japanese nonlearners generally outperformed English nonlearners in their overall perception of Mandarin lexical tones, L1-based differences were less extensive for the two groups of learners. Both learner groups were least accurate on T2-T3 and most accurate on T3-T4. Conclusion: The results suggest that with classroom experience, English speakers can overcome their initial disadvantage and learn lexical tones in a new language as successfully as speakers of Japanese with classroom experience.