The purpose of this secondary data analysis was to explore the mediating influence of internalizing behavior on the link between child maltreatment and externalizing behavior (for example, rule-breaking behavior and aggressive behavior) among children. Using a longitudinal comparison group design and a sample of 300 youths (56 percent maltreated), the relationship among maltreatment and internalizing and externalizing behavior was explored. Structural equation modeling revealed a mediating effect in which initial internalizing symptoms had a longitudinal residual effect on externalizing behavior among maltreated youths. Practice and policy strategies should include early identification, comprehensive assessment, and treatment for child maltreatment that include emotional, psychological, and behavioral issues. A comprehensive social work response may serve to reduce the risk of adverse behavioral outcomes among youths that place them at risk of juvenile delinquency and juvenile justice involvement.