Post-colonial Hong Kong's language policy is marked by biliteracy and trilingualism: the skill to read and write Chinese and English and to speak Cantonese, English and Putonghua/Mandarin. South Asian students' bad achievement in written Chinese and Cantonese challenges these social asiprations. A deficit of Chinese literacy is a main obstacle for access to educational and career chances. Results are debated in the light of Cummins' mutuality hypothesis on the growth of essential interpersonal communicative abilities and cognitive academic language skills in Chinese.