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 less than 0.05) and other unwanted outcomes including injuries (p less than 0.05), use of physical restraint (p less than 0.001), and duration of seclusion (p less than 0.001). 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 unit scan be reduced by implementing a broad-based behavioral management program. These findings highlight the importance of organizational approaches to behavior and risk management. (Contains 2 tables and 2 figures.)