PERAN INTERAKSI TEMAN SEBAYA DALAM PEMBENTUKAN PERILAKU SOSIAL ANAK USIA 3-4 TAHUNNIM.: 23204032011Isna MaulidyaauthorThis study is motivated by the importance of early childhood social development as a foundation for interpersonal behavior, as well as the limited qualitative studies specifically examining peer interaction among children aged 3–4 years. This study aims to analyze the role of peer interaction in shaping the social behavior of children aged 3–4 years in daycare/playgroup settings. This study employs a qualitative approach with a case study design, with data analysis conducted in depth to understand the phenomenon under investigation. Data were collected through participatory observation, in-depth interviews with educators, and documentation, and were analyzed using the stages of data condensation, data display, and conclusion drawing. The results show that peer interactions include parallel, associative, simple cooperative, onlooker, and conflict interactions. These interactions contribute to the development of children’s social behaviors, such as sharing, cooperation, early empathy, verbal and nonverbal communication, emotional regulation, and the ability to resolve simple conflicts. The quality of peer interaction, characterized by frequency, active engagement, and continuity, plays a significant role in shaping the social behavior of children aged 3–4 years. This study implies that early childhood education environments need to systematically design social interaction-based learning activities to optimize children's social development.372.21 Pendidikan Pra Sekolah/Pendidikan Anak Usia Dini2026-03-11UIN SUNAN KALIJAGA YOGYAKARTA;FAKULTAS ILMU TARBIYAH DAN KEGURUANThesis