Main Article Content
This study investigates the functions served by learners’ first language (L1) in classroom interaction among Iranian learners of English (L2). The study aims to determine how learners’ L1 serves them in their L2 learning. It adopts a qualitative approach. The study involved the participation of eleven Grade 9 learners in one Iranian high school in Malaysia. Sources of data included transcripts of classroom interactions and interviews with learners. Learners used L1 in social and private speech, for a variety of purposes. Learners used L1 in their social speech to talk about language and task, and in their interpersonal relations. L1 created a context for more participation and collaboration. Learners’ L1 private speech functioned beneficially in their cognitive process and assisted the less proficient learners in successfully performing the tasks. The findings affirm the sociocultural perspective of language learning that the social interaction involving L1 and L2 mediates the learners’ mental processes. This study contributed to the body of knowledge on second language learning by providing evidence that the transition from being other-mediated to self-mediated may occur through L1 mediation. Implications for group work are discussed.