This preliminary study explores segmental phonetic convergence and vowel overlap in simultaneous bilinguals, highly proficient American late learners of French, and monolinguals. A shadowing task solicited French /i e ɛ y ø œ a ɔ o u/ and American English /i ɪ ɛ æ ɑ ɔ ʊ u/ vowels in four different phonetic contexts: isolated, /bVb/, /pVp/ and /pVʁ/ for the French vowel /œ/. F1, F2, F3 and duration were extracted and analyzed for convergence towards the target values. In addition, phonological accuracy was evaluated by measuring the space between contrastive vowel classes through the use of the Pillai Bartlett trace (Pillai 1976). This study found that bilinguals and language learners showed more signs of divergence for English than French but found more vowel merging in French than in English for both speaker profiles.