Communication skills are essential skills to create and maintain interactions between learners and others, and proper expression of communication makes relationships with others positive. In addition, since proper communication skills elicit a positive response from others, it ultimately makes learners highly evaluate for themselves, and induces learners to attempt a more active participatory approach to problems arising from learning situations. The purpose of this study, using data from the 6th year survey (2018) of the Korean Educational Development Institute s Korean Education Longitudinal Study 2013 Cohort Data, was to analyze the structural relationship between the communication competency-based instruction, student participation, teachers/friend relationship and self-concept. As a result, first, communication competency-based instruction had an effect on students participation in class, which was found to be mediated by self-concept. Second, the relationship between communication competency-based instruction and self-concept was mediated by the teacher/friend relationship, and consequently, communication competency-based instruction influenced the participation of students through the self-concept mediated by the teacher/friend relationship. In particular, it was found that the formation of the learners self-concept was affected relatively higher the friend relationship than the relationship with the teacher. The results of this study suggested that communication skills-based instruction had a positive effect on students participation in class. In particular, communication skills-based instruction had an effect on students social relationship formation and self-assessment, which proved that communication skills can affect learners social, psychological, and academic attitudes. In addition, this study suggested that social relations of adolescent learners act as a major influencing factor on learners psychology, and that friendship is a key factor in the formation of adolescent self-concept. Furthermore, the results of this study showed that the formation of the learners positive self-concept through the enhancement of the learners communicative attitude can be a major factor in determining the learning participation attitude.