["Psychology in the Schools, EarlyView. ", "\nABSTRACT\nADHD is a prevalent disorder that impacts academic and social functioning in childhood. Teachers often struggle to identify ADHD. This study evaluated the Scope Classroom Observation Checklist's (SCOC) reliability, validity, and acceptability as a potential screening measure for school staff to identify ADHD characteristics. Parents and teachers completed the Attention‐Deficit/Hyperactivity Disorder Rating Scale‐5 (ADHD‐RS‐5). Those who scored ≥ 75th percentile by both raters were considered ‘high symptom’ and were assessed with the reference standard: Section J of the Development and Wellbeing Assessment (DAWBA). Based on the measures, children were split into 3 groups: high‐probability ADHD, intermediate‐probability ADHD and no‐ADHD. 420 children were observed with the SCOC, yielding on/off‐task and hyperactive/impulsive scores. Inter‐rater reliability (IRR) on the SCOC was quantified using the intra‐class correlation coefficient (ICC). The area under the curve (AUC) was used to quantify the ability of the SCOC to discriminate children with high‐probability ADHD from those without; intermediate‐ from high‐probability ADHD and high symptom ADHD from no ADHD. SCOC acceptability to trained school staff was assessed using the Usage Rating Profile‐Assessment (URP‐A). SCOC accuracy was limited. AUCs for distinguishing high‐probability ADHD versus no‐ADHD were 0.59 (on/off‐task) and 0.72 (hyperactive/impulsive). For high symptom versus no‐ADHD, AUCs were 0.64 (on/off‐task) and 0.65 (hyperactive/impulsive). For intermediate‐ versus high‐probability ADHD, AUCs were 0.40 (on/off‐task) and 0.67 (hyperactive/impulsive). Eight staff rated the SCOC acceptable (mean usability = 4.56/6, SD = 0.4). While the SCOC showed good agreement between school staff and researchers, it lacked validity in identifying ADHD."]