Objective: The study aims to examine family functionality, emotion regulation difficulties, preference for loneliness, social exclusion, internalizing and externalizing disorders, and executive functions in children with Attention Deficit Hyperactivity Disorder (ADHD) and Cognitive Disengagement Syndrome (CDS) and compare with ADHD, and ADHD+ Oppositional Defiant Disorder (ODD). Method: This study included 842 children aged 8-12 years. The subjects were categorized according to DSM-V as ADHD (n = 246), ADHD + ODD (n = 212), ADHD + CDS (n = 176), and Control group (n = 207). The solitude and social exclusion, difficulties in emotion dysregulation and Barkley SCT scales, Child Behavior Checklist, family assessment device, and Central Vital Signs (CNSVS) test were used. Results: According to the study, children with ADHD + CDS had higher rates of internalizing disorders. They also preferred being alone and experienced more difficulty communicating with their parents and solving problems within the family. Additionally, these children had difficulty recognizing and understanding the emotional reactions of others. The ADHD + ODD group presented a poorer performance on CNSVS domain tests except for the psychomotor speed test than other groups. Also, ADHD + CDS children had the lowest psychomotor speed scores and lower scores on reaction time and cognitive flexibility than pure ADHD children. Conclusion: This study will contribute to the etiology, treatment, and clinical discrimination of ADHD + CDS. (J. of Att. Dis. 2024; 28(12) 1555-1576)