This article explores the impact of Hong Kong's transition from British colony to Chinese Special Administrative Region on patterns of language use in the domain of professional employment. In particular, it presents the findings of a large-scale multifaceted investigation into the roles of Putonghua, Cantonese, written Chinese and English in the civil service, government-related organisations, and public and private companies. The study therefore offers much-needed perspectives on the viability of China's "one country, two systems" framework and the vitality of Hong Kong's "biliterate and trilingual" policy more than a decade after the handover. The findings indicate that English remains the default medium of written professional communication in both the public and private sectors, while Cantonese is the unmarked medium of intra-ethnic spoken communication. Despite Hong Kong's political and economic reintegration with the mainland, written Chinese and Putonghua currently play only a limited role in business and professional communication. (Contains 3 figures.)