The purpose of this study was to investigate how experiencing collaborative activities effect young children s peer competence in kindergarten. The participants for this study were 56 five-year-old children, the experimental group was 28(13 boys and 15 girls) five-year-old children of S kindergarten in Seoul Gangbuk-gu and the control group was 28(13 boys and 15 girls) five-year-old children of D kindergarten in Seoul Sungbuk-gu. The collaborative activities for experimental group is consisted of 15 activities constructed by researcher. After verifying as suitable for children s development and appropriate for theoretical validity educationally, these 15 activities were applied in the kindergarten s daily routine. For 12 weeks, the young children experienced collaborative activities 3～5 times per week, and totally 42 times. To measure young children s peer competence, the Peer Competence Scale for Preschool Children (Park & Rhee, 2001) was used. The results of this study were as follows: First, there was significant difference of young children s peer competence by experiencing collaborative activities between the experimental and control groups, p< .001. Second, there was significant difference of young children s peer competence on sociability by experiencing collaborative activities between the experimental and control groups, p< .001. Third, there was significant difference of young children s peer competence on prosocial behavior by experiencing collaborative activities between the experimental and control groups, p< .001. Fourth, there was significant difference of young children s peer competence on leadership in peer relations by experiencing collaborative activities between the experimental and control groups, p< .001.