We examined negative transfer from English and Spanish to Portuguese pronunciation. Participants were native English speakers, some of whom spoke Spanish. Participants completed a computer-based Portuguese pronunciation tutorial and then pronounced trained letter-to-sound correspondences in unfamiliar Portuguese words; some shared orthographic form with their translation in Spanish or Spanish and English. Spanish-speaking participants were more accurate and made more Spanish-like than English-like errors. Contrary to predictions, non-Spanish speakers made more Spanish-like than English-like errors on cognates. Participants with higher working memory were more accurate and made more Spanish-sounding errors on cognates. The results suggest that the first language is inhibited during second-language production and that higher working memory is associated with an improved ability to inhibit the first language.