The first steps towards bilingual language acquisition have already begun at birth. When tested on their preference for English versus Tagalog, “monolingual” newborns, whose mothers spoke only English during pregnancy, showed a robust preference for English. In contrast, “bilingual” newborns, whose mothers spoke both English and Tagalog regularly during pregnancy, showed equal preference for both languages. A group of Chinese-English bilinguals showed an intermediate pattern of preference. Preference for two languages does not suggest confusion between them, however. Study 2 showed that both English monolinguals and Tagalog-English bilinguals could discriminate English from Tagalog. The same perceptual and learning mechanisms that support acquisition in a monolingual environment thus also naturally support bilingual acquisition.