In this paper, Zhu's (2019) model of context, practice, and perception is combined with Kadar and Haugh's (2013) discursive-interactional approach to investigate the practice and perception of unexpected topic switching in the context of everyday communication in mainland China. Data were derived from recorded mundane conversations in Mandarin and playback with native Chinese speakers. Results show that the speakers initiate, react to, and perceive unexpected topic switching as a part of appropriate interactional norms. The analyst understandings, participant understandings, and metaparticipant understandings that are uncovered indicate the influence of the sociocultural context, interactional context, and personal context on the practice and perception of unexpected topic switching.