OBJECTIVE: To develop and validate INCLEN Diagnostic Tool for Attention Deficit Hyperactivity Disorder (INDT-ADHD). DESIGN: Diagnostic test evaluation by cross sectional design. SETTING: Tertiary care pediatric centers. PARTICIPANTS: 156 children aged 65-117 months. METHODS: After randomization, INDT-ADHD and Connors 3 Parent Rating Scale (C3PS) were administered, followed by an expert evaluation by DSM-IV-TR diagnostic criteria. MAIN OUTCOME MEASURES: Psychometric evaluation of diagnostic accuracy, validity (construct, criterion and convergent) and internal consistency. RESULTS: INDT-ADHD had 18 items that quantified symptoms and impairment. Attention deficit hyperactivity disorder was identified in 57, 87 and 116 children by expert evaluation, INDT-ADHD and C3PS, respectively. Psychometric parameters of INDT-ADHD for differentiating attention deficit hyperactivity disorder and normal children were: sensitivity 87.7%, specificity 97.2%, positive predictive value 98.0% and negative predictive value 83.3%, whereas for differentiating from other neuro-developmental disorders were 87.7%, 42.9%, 58.1% and 79.4%, respectively. Internal consistency was 0.91. INDT-ADHD has a 4-factor structure explaining 60.4% of the variance. Convergent validity with Conner's Parents Rating Scale was moderate (r =0.73, P= 0.001). CONCLUSIONS: INDT-ADHD is suitable for diagnosing attention deficit hyperactivity disorder in Indian children between the ages of 6 to 9 years.