Objective: Neuropsychological assessment plays a critical role in the formulation of diagnosis and treatment, especially as it pertains to ADHD, which can be misdiagnosed in children who present with symptoms that overlap various psychiatric domains (Pritchard, Nigro, Jacobson, & Mahone, 2012). This case emphasizes the importance of delineating diagnostic features resembling ADHD in order to accurately diagnose and subsequently inform intervention design. Method: The client is an 11-year-old English-speaking African American male with a diagnosis of ADHD and a history of psychopharmacological treatment. Presenting problems include: difficulty staying focused, impulsive behaviors, anger outbursts, tantrums, depressed mood, excessive crying, withdrawal, anhedonia, loss of energy, irritability, friendlessness, repeated experiences of being bullied, vision issues, and difficulty with handwriting. Comprehensive neuropsychological instruments were used to evaluate whether the client's symptoms represent true frontal lobe impairment and to assess for learning deficits and cognitive processing delays that interfere with executive functioning, attention, socialization, and mood regulation, as well as to clarify the validity of the client's ADHD diagnosis. Results: Neuropsychological test results revealed average to low average performance across intellectual, academic, executive, memory, and socio-emotional domains. Overall strengths in intellectual and cognitive functioning, combined with data from a school observation and clinical interview, suggest that reports of the client's impulsive behavior and emotional dysregulation are likely due to environmental stressors and poor coping skills, rather than deficits in executive functioning. These findings became the basis of a psychological and behavioral intervention plan for a client previously misdiagnosed with, and ineffectively treated for, ADHD. Conclusion: This case highlights the important role a comprehensive neuropsychological evaluation plays in clarifying diagnosis, especially as it pertains to distinguishing between ADHD and other comorbid disorders, in order to determine the course of treatment for children exhibiting overlapping symptoms of both ADHD and depression.