This Resource Guide was developed with an understanding of trauma as presented in SAMHSA’s Concept of Trauma and Guidance for a Trauma-Informed Approach:
Individual trauma results from an event, series of events, or set of circumstances that is experienced by an individual as physically or emotionally harmful or life threatening and that has lasting adverse effects on the individual’s functioning and mental, physical, social, emotional, or spiritual well-being.
Trauma-Informed: The Trauma Toolkit, Second Edition, a resource created by Canada’s Klinic Community Health Centre, offers three qualifying points that serve as a useful addition to SAMHSA’s concept of trauma:
Regardless of its source, trauma contains three common elements:
The criteria above can apply to a wide range of traumatic experiences. Causes of trauma may include:
In a 2016 report , SAMHSA estimates that 40.8% percent of adults have been exposed to one or more potentially traumatic events (PTE) over the course of their lives. A study reported in the Archives of General Psychiatry indicates a higher lifetime prevalence estimate for trauma at 68.2 percent .
 Forman-Hoffman, V. L., Bose, J., Batts, K. R., Glasheen, C., Hirsch, E., Karg, R. S., ... & Hedden, S. L. (2016). Correlates of lifetime exposure to one or more potentially traumatic events and subsequent posttraumatic stress among adults in the United States: results from the Mental Health Surveillance Study, 2008-2012. In CBHSQ data review. Substance Abuse and Mental Health Services Administration (US). Retrieved from: https://www.samhsa.gov/data/sites/default/files/CBHSQ-DR-PTSDtrauma-2016/CBHSQ-DR-PTSDtrauma-2016.pdf.
 Copeland, W. E., Keeler, G., Angold, A., & Costello, E. J. (2007). Traumatic Events and Posttraumatic Stress in Childhood. Archives of General Psychiatry, 64(5), 577. Retrieved from: https://jamanetwork.com/journals/jamapsychiatry/fullarticle/482289. (See Figures & Tables section.)
According to the Centers for Disease Control and Prevention, ACEs "are potentially traumatic events that occur in childhood (0-17 years) such as experiencing violence, abuse, or neglect; witnessing violence in the home; and having a family member attempt or die by suicide" (Centers for Disease Control and Prevention, 2019).