Language contact, bilingualism and contact-induced language change have created controversial issues among linguists as more and more people of different languages and cultures around the world come into contact. There have been studies of the phenomena of language change including code switching, code mixing, interference, transference, and convergence in different language dyads (Clyne, 2003), especially in multi-lingual societies like Australia, the United States of America and Canada. However, there is insufficient research into the Vietnamese language used in Australia and its changes in comparison with Vietnamese used in Vietnam. This empirical study, therefore, investigates the patterns of pragmatic transference in spoken Vietnamese used by the second generation speakers in Australia who are English-Vietnamese bilinguals. The basic hypothesis of this thesis is that the formulae of pragmatic speech acts in spoken Vietnamese used by the second generation and their lack of knowledge or incorrect usage of Vietnamese idioms and proverbsshow a shift from indirectness to directness in the pragmatic performance of the language. Specifically, the study focuses on the speech act of refusal and the usage of Vietnamese idioms and proverbs. The study documents such pragmatic transference and explores the causes of these changes. The findings will help to fill the gap in the study of language change in linguistics as a whole, and particularly the study of the Vietnamese of the English-Vietnamese bilinguals, and the English-Vietnamese dyad in terms of linguistic and pragmatic elements.The findings have implications for language maintenance among the Vietnamese diaspora community in Australia, for the study of language change in heritage languages, and for understanding trends in the multicultural and multilingual society of Australia.