The Chinese diaspora comprises sizeable ethnic Chinese populations spread across the globe. Although Chinese diasporic communities share a common heritage and, by definition, a common heritage language, their sociolinguistic backgrounds and identities are diverse, complex, and multifaceted. Members of the diaspora speak one or more, or indeed none, of several mutually unintelligible Chinese varieties and dialects. Recent changes in the demographics of the overseas Chinese communities have, moreover, led to new patterns of multilingualism. This chapter discusses key sociolinguistic aspects of language contact relevant to this group at large, including language maintenance versus language loss, the trends and challenges of heritage language learning, the role of Chinese community schools, differences in attitudes towards Chinese dialects, and the dynamics of multilingual identities and multilingual practices such as translanguaging and language brokering. The review focuses on the diasporic communities in Anglophone and other Western settings, as it is mainly the rising numbers of ethnic Chinese in those parts of the world that have fuelled the growing interest in Chinese heritage language learning and research in recent decades.