Little is known about the acquisition of phonology in children learning a second language before the age of four. The study of Mandarin children's early learning of English coda consonants is of particular interest because of the different syllable structures permitted in the two languages. Using an elicited imitation task, this study explored the acquisition of coda consonants and related phrase-final lengthening in twelve three-year-old Mandarin-speaking children exposed to Australian English at preschool. Performance was good on /t/ and /s/ codas, but worse on the phonologically and morphologically more complex /ts/ coda. Although /n/ is one of the few codas permitted in Mandarin, both perceptual and acoustic analysis revealed surprisingly poor performance, suggesting possible L1 Mandarin effects. As expected, longer exposure to English resulted in better coda production. The results are discussed in terms of possible mechanisms underlying L2 phonological and morphological acquisition in early child second language learners (ECL2).