This qualitative research was conducted to investigate how the teacher and students’ cultural identities are discursively constructed and revealed by code-switching in an English language classroom. It made use of the critical ethnographic approach to studying language use guided by Fairclough’s (1992) Critical Discourse Analysis. The findings of the study revealed that both the teacher and students utilized code-switching during class interactions not only to express their linguistic backgrounds but their cultural identities as well. Transcripts of the class discussion also revealed that the teacher and students’ use of code-switching during class interactions was related to relevance of the topic discussed or question asked, familiarity of context presented, and one’s perceived attachment to a particular cultural group. Furthermore, emotion, context, and group membership were the factors that strongly influenced the teacher and students to use code-switching in the expression of their cultural identities during the class interactions.