Positive behavioral support (PBS) is one of the positive approaches based on the principles of the applied behavior analysis in preventing inappropriate behaviors in the school environment. In the present study, systematic social skills training was included as a part of the intervention, and whether this caused any difference in the social skills performance of students in the second grade in which PBS was applied. Moreover, the students in the second grade in which routine teaching continued, and the implementation reliability in the PBS intervention of the teachers and practitioner were also investigated. The experimental design with the pre-test, post-test and control group was used in this study. There was an experimental group and a control group in the study. The findings of the study showed that class-wide PBS is effective on the skills of the second-grade students in the experimental group of acquiring the target skills in the category of complying with the rules, group working and starting a relationship, and the skills of maintaining the skills obtained 3 weeks after the end of the intervention. The social validity findings showed that the opinions of the students on the target skill, intervention and their performance were positive.