Objective: Aggression is common in children and adolescents admitted to psychiatric inpatient units. Few interventions for reducing aggressive behaviors have been identified. This study aimed to evaluate the impact of a milieu-based behavioral management program on the frequency of aggressive behaviors in a child and adolescent mental health inpatient unit. Method: The behavioral management program incorporated individualized patient management plans, early detection and prevention, staff training, reinforcement of appropriate behaviors, and intervention using the least restrictive option. Outcomes were assessed for 6 months before and after program introduction, and included episodes of aggressive behavior, injuries, use of physical restraint, seclusion, p.r.n. sedation, use of security, services, and staffing factors. Results: Implementation of behavioral management led to a significant reduction in the episodes of aggressive behavior (p < .05) and other unwanted outcomes including injuries (p < .05), use of physical restraint (p < .001), and duration of seclusion (p < .001). These outcomes were achieved without reducing the number of admissions, changing the types of patients admitted, increasing staff costs, or increasing the use of p.r.n. medications. Conclusions: Aggressive behaviors in child and adolescent psychiatric inpatient units can be reduced by implementing a broad-based behavioral management program. These findings highlight the importance of organizational approaches to behavior and risk management.