The phonological system of the French of Frenchville, Pennsylvania (USA) demonstrates a dramatic case of transfer in the latest (and last) generation of bilingual French–English speakers: the mid front round vowels, [œ] and [ø], have often been replaced by the English rhoticized schwa as found in the word sir. However, French schwa, which is arguably phonetically non-distinct from the mid front round vowels, does not participate fully in this merger. This result is unexpected given both the phonetic identity of schwa and [ø], and the fact that our speakers are not literate in French and, as such, have no access to the differential orthographic representations manifest between schwa and the mid front round vowels. The data argue strongly that schwa is, in some sense, “real” for these speakers. Based on a phonetic analysis of the vowels under consideration, we argue that transfer between two sound systems cannot be perceived as a simple case of phonetic replacement. Instead, transfer or convergence with English must be viewed as a systemic process that preserves contrast in unexpected ways. In the case at hand, the data suggest that the traditional separation between the phonetic and phonological levels of grammar cannot be maintained as each level contributes to both provoking merger and maintaining contrast in bilingual speech.