This study examines how speakers of Taiwan Mandarin, a syllable-timed tone language, realize focus in L2 English. Taiwan Mandarin marks focus by increasing the pitch range and duration of the whole focused constituent, which can be polysyllabic. English, instead, marks focus via a pitch accent on the focused words’ stressed syllable, which also lengthens. An interactive question-answering experiment was conducted. Two sets of initial-stressed English words featuring identical segments in the first syllable and varying word lengths were elicited phrase-medially under three focus conditions (contrastive, narrow, unfocused). Results show that stressed syllables undergo focus-related lengthening in monosyllabic words, but remain unaffected in polysyllabic words. Instead, focused polysyllabic words present lengthening on the first post-stress syllable. Meanwhile, F0 marks focus less robustly, being higher in focused than unfocused conditions only in polysyllabic words. Similarly to lengthening, the locus of the F0 effect is on the syllable following the stressed one. Neither duration nor mean F0 distinguishes between focus types. Results suggest that speakers of Taiwan Mandarin mark focus phonetically in L2 English, but the effects are not realized in the stressed syllable for polysyllabic words as is typical of English. These findings are discussed in terms of L1-L2 prosodic transfer.