We compare the F0 output and chunking size of speech units of L1 English, TW L2 English and L1 Mandarin to see what some of the major intrinsic prosodic difference could be, what prosodic features could account for TW L2 English and in what way prosodic transfer occurs. Results show that the fundamental prosodic difference of the two languages is how in the pitch domain English requires sharper high/low contrast by higher-level prosodic units but less such contrast in accentuating lower-level prosodic units whereas Mandarin patterns are the exact opposite. Explanations are provided regarding how TW L2 English differs from L1, why prosodic transfer merits detailed analysis, and why mastering English prosody is especially difficult.