This study investigated the level of preservice secondary social studies teachers’ awareness on multicultural education and Korean as a Second Language (KSL) education, and analyzed the factors affecting their KSL-Social studies teaching efficacy. Learners with multicultural backgrounds encounter multiple barriers while studying social studies as the subject consists of complex concepts and culturally-linguistically situated context knowledge that requires advanced level of literacy skills for understanding. This study focused on KSL curriculum, which provides guidance on teaching Korean as a Second Language, inquiring to what extent second language pedagogic knowledge connects to social studies teaching efficacy. Data shows that social studies preservice teachers overall presented positive and advanced understanding of multicultural education, while they failed to recognize what the KSL education is, what consists of its curriculum, and how to bridge it to social studies classroom. Regression analysis reveals that the participants, who were highly exposed to multicultural education contents, possessing a positive view of multicultural education and some basic information about KSL education, demonstrated a high-level of KSL-Social studies teaching efficacy. The results of this study provide practical insights for the betterment of multicultural teacher education.