The native language affects non-native languages in such a way that the phoneme categories formed in infancy impede the perception of sound contrasts within the native language categories. Balanced bilinguals form in this respect an interesting group: do the two languages affect each other on the perceptual level, or can the two systems be kept apart in a behavioral attention-demanding task? In order to study the vowel perception of balanced bilinguals, a behavioral identification task was performed. In the light of the obtained results, it seems that bilinguals are behaviorally able to keep the two languages apart, and consciously choose to use one or the other in an attention-demanding identification task. Keywords: Bilingualism, vowel perception, identification, context language.