The aim of this study was to construct and test the effectiveness of Tier 2 School Wide-Positive Behavioral Support(SW-PBS) for children with externalizing problem behaviors. The secondary prevention intervention method was constructed and implemented for children who exhibit externalized problem behavior even after the primary support for positive behavior. This secondary method, considering the school environment, school-level expected behavior, and the problem behaviors of each child, consisted of both CICO(Check-In/Check-Out) and social skills training program. To this end, a secondary support intervention for positive behavior was implemented for 4 male elementary school students in grades 5-6. To verify the efficacy, paired sample T-tests were conducted on externalizing problem behaviors, social skills, and self-esteem. As a result, first, the externalizing problem behavior was significantly reduced, showing a large effect size. Second, although social skills and self-esteem were not statistically significant, qualitative analysis presented a significant change. This study has implications in that it proposed a school-wide understanding and approach to children who exhibit externalized problem behaviors. It also offered a preliminary examination of the efficacy of interventions. Lastly, in discussion, it offers the limitations of this study and a proposal for further research.