Abstract. The dearth of sociolinguistic investigations into written codeswitching (CS) has prompted the researcher to explore the forms and functions of codeswitching in college students' Facebook (FB) posts using Thurlow’s Typology of Communicative Themes and Functions. Further, the study examined how CS may affect English language teaching. The researcher used the descriptive-analysis method as the research design to detail the characteristics of a specific phenomenon, i.e., codeswitching on Facebook. Using convenience sampling, 175 students from two universities participated in the study. Results reveal that intersentential codeswitching is the most prevalent form among college students, followed by intra-word, intrasentential, and tag-switching. Moreover, most of their written code switches were categorized under InformationalRelational Orientation (IRO), indicating that students use Facebook to seek information, ask favors, and build relationships. Employing codeswitching in English language teaching may be considered a pragmatic language behavior for easy interaction and knowledge acquisition, especially for complex concepts in language learning. However, codeswitching should not be considered an alternative technique for teaching the English language, but the use of codeswitching may be allowed in class activities only to a limited extent. English language teachers should integrate online media literacy to familiarize learners with online communication norms and codeswitching patterns, recognize students’ diverse language repertoires, and adopt a balanced approach emphasizing fluency in standard English while recognizing the importance of codeswitching in communication.

Keywords: College students; English language teaching; Facebook; Written code-switching.