This study aimed to explore the linguistic culture of Korean adolescents by examining their linguistic interactions, focusing on identity construction and peer group power relationships. The setting for the study was two sixth-grade classrooms in two elementary schools and three second-year classrooms in two middle schools in Korea from August to November 2017. In each classroom, we selected four focal students based on Social Network Analysis and analyzed the video files of their peer group interactions, drawing on micro-ethnographic discourse analysis. Findings from observations, video recordings, and interviews with these students revealed that Korean adolescents often construct their identities according to relative evaluations and ratings. In addition, the use of language to reveal one’s identity varied according to gender. Unlike male adolescents, who engaged in superiority language or bluffing, female adolescents preferred to lower themselves by using honorific language. With regard to power relationships, the aspects of language used by adolescents varied. Adolescents with high centrality tended to lead communally accepted actions, while adolescents on the periphery tended to conform to and imitate the language use of those with high centrality. This study could contribute to extending our understanding of the dynamic nature of identity construction and power relationships within adolescent interactions.