In spite of the increasing Korean population, there is still a paucity of studies examining emergent Korean bilingual children's dual-language development within their social contexts. In particular, no existing study has paid attention to the honorific system of Korean, which is one of the most important features in learning the Korean language. In order to address the research gap, this qualitative case study explores how four-year-old, Korean-English bilingual children utilize Korean and English and Korean honorifics depending on social contexts. With a sociocultural theoretical framework, data were collected for seven months by observations, interviews, children's artifacts, and audio- recordings, and analyzed based on thematic and sociolinguistic analysis. The results suggest that dual-language learning for early bilingual learners is a dynamic social and cultural process, involving multilayered decision-making. The findings of this study will be beneficial not only for early bilingual educators but also for the broader community of educators who are interested in the social nature of learning.