ABSTRACT PRE-SERVICE TEACHER’S CODE-SWITCHING: A STUDY IN ITTC DARUSSALAM GONTOR FOR GIRLS CAMPUS 3 Rhiznandya Fatimatuzzahro’ 42.2021.133.053 To enhance students’ understanding, teachers may implement various teaching strategies, one of is code-switching in the classroom. Many students comprehend lessons more effectively when teachers switch between languages. This research was conducted to find out how code switching of pre-service teachers can provide understanding to students. This study aimed to determine the types, functions, and impact of code-switching on students' English language acquisition, engagement, and confidence. The research employed descriptive qualitative. Data were collected through observation, documentation and interviews. The subject of this study was a pre-service teacher who used code-switching in teaching, while the participants were students of class 4N at ITTC Darussalam Gontor For Girls Campus 3. Teacher was considered to have mastered the English language and can explain it clearly and correctly, these students are considered to have a good understanding of English after four years of studying the language and mastering speaking, reading, writing, and listening skills. The data were analyzed through data reduction, classification, and display. Observations identified 75 instances of code-switching, categorized into three types: inter-sentential code-switching (31), intra-sentential code-switching (33), and tag-switching (11). Meanwhile, 74 utterances served different functions, divided into five categories: explanation (27), clarification (32), asking (7), translation (6), and emphasizing (2). Moreover, interviews with students indicated that code-switching impacted their language acquisition. However, some students believed that code-switching merely served as a bridge between their understanding and language proficiency, rather than contributing to long-term mastery. Key word: code-switching, language proficiency, pre-service teacher