The current study investigated whether bilingualism affects the processing of sub-lexical representations specifying the sound structure of words. Spanish-English bilinguals, Mandarin-English bilinguals, and English-only monolinguals repeated English tongue twisters. Twister materials had word or nonword targets (thus varying in whether lexical information did or did not support sound processing), and similar or dissimilar sounds (thus varying in difficulty with respect to competition at a sub-lexical level). Even though bilinguals had learned English at an early age, and spoke English without an accent, Spanish-English bilinguals produced significantly more twister errors than monolinguals, particularly in the absence of lexical support. Mandarin-English bilinguals were also disadvantaged, but more consistently across all twister types. These results reveal that bilingual disadvantages extend beyond the lexical level to affect the processing of sub-lexical representations. More generally, these findings suggest that experience with sound structures (and not simply their intrinsic complexity) shapes sub-lexical processing for all speakers. (Contains 2 tables and 1 figure.)