Due to the increase of economic immigration over the last few decades, South Korea has rapidly become a multi-ethnic society. The number of students with a multicultural background (SMBs) has increased more than tenfold in the past ten years. Research has revealed that despite physical inclusion of SMBs in general classrooms, SMBs tend to struggle at school as a result of language difficulties, academic underachievement, and social isolation. Shedding light on the Salamanca thinking, this study aims to investigate how teachers' experiences of SMBs vary according to school cultures. Thirteen teachers from three schools (with different school cultures) were invited to participate in qualitative semi-structured interviews. It was revealed that the teachers, who worked in the different school cultures, expressed differently with regard to (1) teachers' reasoning about SMBs' struggles, (2) teachers' professional knowledge and strategic practices, (3) collaboration with a multicultural education supervising teacher (MEST), and (4) dependency upon external support. The school judged to be contributing to 'true' inclusion was characterised by ample support from a MEST and the creation of an inclusive learning environment for SMBs as a whole-school approach. What can further 'true' inclusion of SMBs in elementary schools and the implications thereof are discussed.