Mainland Chinese students' (MCSs') cross-cultural adaptation experiences in Hong Kong have remained under-researched. Our study investigates this phenomenon with a language and social psychology approach and explores the role of Cantonese ability and communication with locals. We invoked Communication Accommodation Theory (CAT) to investigate the intergroup communication between MCSs and locals. Thematic analysis of ten semi-structured interviews revealed that MCSs considered self-perceived Cantonese abilities and communication with locals critical for their adaptation. Invoking CAT to investigate this intercultural context provided valuable insights into the importance MCSs place on locals' communicative behaviours when deciding whether to communicate in the local language.