For bilinguals born in an English-speaking country or who arrive at a young age, English (L2) often becomes their dominant language by adulthood. This study examines whether such adult bilinguals show equivalent performance to monolingual English native speakers on three English auditory processing tasks: phonemic awareness, spelling-to-dictation and auditory comprehension. The study contrasts three bilingual language groups differing in their L1: morphosyllabic/logographic L1 (Cantonese), morphosyllabic/alphabetic (Vietnamese) L1 and non-morphosyllabic/alphabetic L1 (Other). Particularly on the tasks that involved nonwords, the morphosyllabic bilingual groups performed most poorly, suggesting an effect of L1 phonological structure on English processing despite L1 having become subordinate to L2. The results indicate that even when a bilingual is born, raised and educated in their L2 environment, native equivalence in L2 is not assured.