The purpose of this article is to report results of an investigation into the production of a covert contrast by native speakers of Korean, Portuguese, and Spanish in the acquisition of the English distinction between the high front vowels /i/ and /?/. A covert contrast is a statistically reliable acoustic distinction made by a language learner between target-language phonemes that is nevertheless not perceived by native speakers of the target language. We gathered data on both the production and perception of this vowel contrast from a total of 36 second-language learners from the three native-language backgrounds, along with data from an additional 22 native-speaker controls. The findings are that about two-thirds of our second-language learners produced a covert contrast between the targeted vowel phonemes. In light of the results from research on child language acquisition and disordered speech, our data suggest that a covert contrast is not limited to the domain of the acquisition of a first language, either by normally developing children or by those with speech disorders.