ABSTRACT
This study aims at finding out the pattern of using L1 in group discussion activity in terms of reasons, the frequency, and purpose, and also the factors driving the use of L1 in group discussion in International Primary Education (BIPE). Sixteen students were chosen to participate in this study. The data of this study was collected by using questionnaire and interview. The finding of this study reveals that there are three factors that drive the students using L1 in group discussion. Those three factors are related to the activities in the group discussion itself, the second factor is related to the familiarities of the topics, and the third is about language-related problems. The finding of this study also reveals that there are three patterns of using L1 by the students in the classroom activity. Those are the reason for using L1 in group discussion activity, the frequency of using L1, and the purpose of using L1. Regarding the students’ opinions, they assume that they can use L1 in classroom activity. The reasons that underlie their opinions are L1 could be a helpful and facilitating tools and an effective means in the learning process.