Background: Burnout among students refers to feeling exhausted because of study demands, having a cynical and detached attitude toward one’s study, and feeling incompetent as a student. Objective: This study examines the validity and the reliability of schoolburnout inventory (SBI) in high schools via confirmatory factor analysis. Method: This research adopted a descriptive approach. The study sample included a total of 520 (270 girls, 250 boys) adolescents, selected through random multi-cluster sampling from among high schools of Tabriz. Participants filled out a questionnaire concerning their school burnout. Findings:The results of the confirmatory factor analysis showed that the three-factor solution, compared to other models, fit the data best and also gave the best reliability indices. The three theoretically-derived dimensions of school burnout were closely related but had separate constructs. Finally, the concurrent validity for the School- Burnout Inventory (SBI) was found and the correlations of school engagement with each of the three dimensions of school burnout were examined: the lower their school engagement, the more exhaustion, cynicism and inadequacy they reported. Conclusion: The present study introduced the new concept of school burnout and its measurement instrument in the educational and counseling contexts.