The purpose of this study was to examine the effects of social supports from the family and school, and after school institutions on the school adjustment, emotional regulation, and social adjustment of multicultural family children. Research data, through the use of a questionnaire, were collected from 346 multicultural family children from the 3rd to 6th grades in elementary school in Gwangju Metropolitan City and Jeollanam-do. After the factors of children's sex, grades, and family structure were controlled, the effects of different sources of social supports on school adjustment, emotional regulation, and social adjustment were analyzed using hierarchical regression analysis. As a result, it was found that the effect of the most influential social support was from the school -teacher on school adjustment, from parents on emotional regulation, and school peers on social adjustment. The results suggested that it was more efficient to provide appropriate social supports for improving different areas of multicultural family children's abilities. Implications for further research and practice were discussed based on the results.