Dr. Felitti is the co-Principal Investigator of the ACE Study. ACE is a major, ongoing, retrospective and prospective study involving over 17,000 middle-class Americans. The study looks at categories of adverse childhood experiences and their relationship to adult health, well-being and social functioning. The Adverse Childhood Effects (ACE) Study has major implications: all patients should be routinely screened for adverse childhood experiences; a childhood trauma history may be very relevant to both serious illness and vague somatic complaints, and appropriate approaches to treatment must include dealing with childhood trauma. Additional data suggest that evaluating patients for ACEs is also cost-effective. According to data collected from over 17,000 Kaiser patients, adverse childhood experiences, though well concealed, are unexpectedly common, have a profound negative effect on adult health and well-being a half-century later, and are a prime determinant of adult health status in the United States.