Discusses the connection between child maltreatment and parental substance abuse, and argues for interagency collaboration between the child welfare, substance abuse treatment, and court systems. Explains how child outcomes can be negatively affected by inadequate collaboration and information-sharing between systems. Suggests that the three groups need to track clients in either a single system, or separate but well-linked systems. Describes the cost-benefit implications of multi-agency interoperability. Argues that interoperability is particularly effective in keeping families together and avoiding out-of-home placement.