Background:To validate a brief, self-reported, Teen Symptom Questionnaire–Mental Health (TSQ-M), for identifying adolescents with mental ill-health, designed for conducting epidemiological studies and clinical work in primary-care settings.Materials and Methods:In this prospective, cross-sectional study of 146 adolescents, re-cruited six rural and urban schools, the newly developed TSQ-M as the measure for validation and General Health Questionnaire-12 item (GHQ-12) as the gold standard measure were administered by independent trained raters. Tests for diagnostic accuracy and validity were conducted.Results:A TSQ-M score of ≥29 (Sn=75.68%, Sp=68.06, +LR=2.37, -LR=0.36, PPV=70.9, NPV=73.1) with the AUC of 0.79, is suggested for screening use in Indian populations. Besides the adequate face and content validity, TSQ-M has moderate internal consistency (Cronbach's α = .64) suggesting that the construct of mental ill-health as conceptualized by TSQ-M has multiple sub-constructs. The presence of sub-constructs was demonstrated by an 8- factor structure, which explained 60% of variance.Conclusion:The TSQ-M is a psychometrically adequate, yet a brief measure, for clinical and research work in identifying mental ill-health among adolescents in primary-care settings in India.