Dissertation (MA Education)The purpose of this study was to investigate students‘ perception of teachers‘ use of code-switching in teaching English language in secondary schools. The research questions that guided the study were: One, What are teachers‘ code switching practices in teaching English language in secondary Schools? Two, How does code switching practice influence students‘ mastery of English language skills in secondary schools? Three, What are the students‘ perceptions on code switching in teaching English language? Four, How can code switching be avoided? Inter-language theory and Communication accommodation theory guided this study. Qualitative interview-based approach explored the research questions. By means of simple random sampling and purposeful sampling strategies, form three students and teachers were selected as participants for this research respectively. The findings revealed that despite the varied application of code-switching in classrooms, still perceptions found to be negative and hindering the English language proficiency development. Such perceptions are mostly connected with unawareness of instructional benefits of code-switching. Moreover it was observed that employing both English language and Kiswahili language at once leads the students with difficulties in using English language and its basic skills such as speaking skill, reading skill, writing skill and listening skill. Also the study indicates that there is no firm work employed by education stakeholders like teachers to adjust grammatical errors into standard language.