Diglossia is a language situation that does not always take place between two dialects of the same language; speaking two different languages in two different encounters is also considered diglossia. This study examines the use of language among Arabic-speaking Australians in Sydney. After analyzing ten authentic doctor-patient examination sessions in a clinic in Sydney, this study reveals that Arabic-speaking Australians are diglossic as they speak Modern Standard Arabic (MSA), Reginal Arabic Dialects (RADs), and English depending on the technicality of the discussion. This study also reveals that the level of education, the number of years spent in Australia, age, and prestige play a significant role in determining high (H) and low (L) varieties among Arabic-speaking Australians. This study also reveals that educated Arabic-speaking Australians speak English as their preferred language in technical conversations regardless of their age of arrival to Australia. The uneducated Arabs who arrived in Australia before the age of 20 either speak English or RADs in technical discussions. The uneducated Arabs who arrived in Australia after the age of 20 either speak RADs or MSA in their technical discussions. This study also reveals that code-switching is relatively popular among Arabic-speaking Australians who arrived in Australia after the age of 20. Code-mixing is popular among Arabic-speaking Australians who were either born in Australia or arrived in Australia before the age of 20. In these situations, code-switching is used as an indication of social prestige and code-mixing is used to express group identity.