Objective: To evaluate efficacy and safety of SPN-810 (extended-release molindone) in a Phase-2b, randomized, double-blind, placebo-controlled, dose-ranging study of children (6–12 years) with ADHD and persistent impulsive aggression (IA). Method: After lead-in, children were randomized to (a) placebo ( N = 31); (b) low-dose ( N = 29, 12/18 mg/day); (c) medium-dose ( N = 30, 24/36 mg/day); and (4) high-dose ( N = 31, 36/54 mg/day) groups. Treatment included ~2.5-week titration, 3-week maintenance, and 1-week tapering/conversion, alongside existing monotherapy (stimulants/nonstimulants) and behavioral therapy. The primary endpoint was change in Retrospective-Modified Overt Aggression Scale (R-MOAS) score at end of study, with safety monitored. Results: A total of 95 (78.5%) children completed the study. Aggression (R-MOAS) improved with low and medium doses (low dose: p = .031; medium dose: p = .024; high dose: p = .740). The most common adverse events were headache (10.0%), sedation (8.9%), and increased appetite (7.8%). Conclusion: These results suggest SPN-810 may be effective in reducing residual IA behaviors in children with ADHD. Research is still needed to support the benefit–risk profile of SPN-810 in pediatric populations.