As part of a Chinese government project to document and protect the country’s language resources, this research examines variation in Cantonese spoken in the city of Guangzhou. Over 100 speakers were recorded and the 44 hours of natural discourse were searched for occurrences of code-switching (CS) between Cantonese and Mandarin (C-M) or English (C-E). This paper describes the differences between age-groups in terms of the distribution of different types of CS and its communicative functions. More frequent CS is observed among younger people due to increasing degrees of language contact with Mandarin and English, challenging the maintenance of Cantonese in younger generations.