Heritage learners in Korean as a Foreign Language (KFL) classes rarely go beyond their current level of Korean and continue to make the same errors regardless of explicit instruction and negative feedback. They have the tendency to demonstrate weaknesses in grammatical accuracy, despite the high-level receptive comprehension skills and communicative fluency. Thus, the purpose of this study is to first identify common errors among Korean heritage learners and analyze them from the sociolinguistic perspective. Then I will discuss some pedagogical implications that could be implemented in KFL classes.