Our research is concerned with the significance of code-switching within the Firefly television series. We have two main questions: (1) How is code-switching used in Firefly? (2) What is the relevance of code-switching to characters’ identities? Does it mark ethnic identity, socioeconomic class, a broader east-west hybrid identity, or is it simply another decoration in the Firefly world? We will begin with a brief background on code-switching and various attested uses of code-switching. We hypothesize that code-switching is a marked choice in Firefly, and we hypothesize that usage of code-switching is meant to reflect the hybridity of the east-west culture in the Firefly world. We found that usage of Mandarin typically aligned with both (1) socioeconomic class of the character, and (2) emotional content of the utterance, with code-switching more prevalent in utterances with high levels of negative emotion. We also found that the connection between language and ethnicity in Firefly was more difficult to draw than we initially expected.