This book seeks to determine whether Code-switching in the classroom (CCS) leads to increased understanding and more effective learning in Indonesian classrooms. Two areas of investigation were examined, the functions and reasons for students and teacher''s CCS and the students'' attitudes towards it. Using a qualitative study, the writer employed ethnographic methodology by which she collected the data using recordings, interviews, questionnaires and direct observations of the classroom interactions. Though several studies have shown that CCS may be detrimental to language learning process, the results of the study revealed the fact that students and teacher engaged in it in order to accomplish several classroom tasks. Both students and teacher used two languages for instructional and survival strategies in the classrooms.