This study aims to investigate five multicultural primary school students’ mother tongue and
Korean language competencies and their effects on learning English as a third language. The
students were 11-12 aged 5th graders in Incheon and one or two of their parents were from China,
Russia, and Taiwan. Results of the official school tests in Korean and English, an English writing
test, and semi-structured interviews were collected and analysed to discuss how the multilingual
students learn English as a third language. It was revealed that the multicultural students were
generally experiencing difficulties in maintaining their mother tongue, developing Korean language
competence, and learning English as a third language. Teachers of English should pay special
attention to multicultural students and consider negative linguistic transfers from their deficient
competencies in mother tongues and Korean to learning English as a third language. Based on the
findings, some practical suggestions are made for teaching English to multicultural students in the
future