Adverse childhood experiences (ACEs) are traumatic events occurring before age 18.  ACEs include all types of abuse and neglect as well as parental mental illness, substance use, divorce, incarceration, and domestic violence.  A landmark study in the 1990s found a significant relationship between the number of ACEs a person experienced and a variety of negative outcomes in adulthood, including poor physical and mental health, substance abuse, and risky behaviors.1 The more ACEs experienced, the greater the risk for these outcomes. By definition, children in the child welfare system have suffered at least one ACE. Recent studies have shown that, in comparison to the general population, these children are far more likely to have experienced at least four ACEs (42 percent vs. 12.5 percent).2