This paper examines the influence of age of immersion and proficiency in a second language on speech movement consistency in both a first and a second language. Ten monolingual speakers of English and 20 Bengali–English bilinguals (10 with low L2 proficiency and 10 with high L2 proficiency) participated. Lip movement variability was assessed based on bilingual participants’ production of four real and four novel words embedded in Bengali (L1) and English (L2) sentences. Lip movement variability was evaluated across L1 and L2 contexts for the production of real and novel words with trochaic and iambic stress pattern. Adult bilinguals produced equally consistent speech movement patterns in their production of L1 and L2 targets. Overall, speakers’ L2 proficiency did not influence their movement variability. Unlike children, the speech motor systems of adult L2 speakers exhibit a lack of flexibility which could contribute to their increased difficulties in acquiring native-like pronunciation in L2.