Social identity plays a key role for foreign students who study abroad. In this paper, we provide a more explanation of social identity, introversion, ethnocentrism, and the need for cognitive closure. Furthermore, we also present the relationship between them. This study focused on introversion, ethnocentrism, and the need for cognitive closure, which are generally seen as negative traits, and investigated their influence on social identity. Through regression analysis, the results showed that all three traits s are negatively correlated with social identity, and that ethnocentrism had the most negative effect on social identity. Accordingly, the research findings demonstrated that students who possess such traits would have less social identity with Korea. Furthermore, for such students it would be difficult to adapt to Korean society or communicate with Korean students. Thus, such phenomena may be considered as factors that could reduce life satisfaction and lead to less than perfect outcomes while studying abroad.