["Criminal Behaviour and Mental Health, Volume 31, Issue 5, Page 310-320, October 2021. ", "\nAbstract\n\nBackground\nThe large and growing number of individuals with severe mental illnesses who are on probation presents challenges to both mental health and criminal justice authorities. The clinical and mental health service needs of probationers with severe mental illnesses have however, been insufficiently researched, particularly with respect to trauma and the need for trauma‐informed services.\n\n\nAims\nTo explore the lifetime prevalence of post‐traumatic stress disorder (PTSD) among people on probation who also have other serious mental illnesses and their demographic characteristics.\n\n\nMethods\nIndividuals on probation in six counties in one southeastern state who had been diagnosed with severe mental illnesses were assessed for PTSD; they were also asked whether they had experienced any of 14 traumatic events of interest over their lifetimes.\n\n\nResults\nOf 207 participants, about half had clinically diagnosable PTSD. Nearly two‐thirds had experienced more than five traumatic events during their lifetimes: 86% experienced at least one non‐interpersonal traumatic event, such as a car accident, and 90% experienced at least one interpersonal traumatic event, such as a physical assault. The latter was the single most frequently reported traumatic event (80%, n = 160). PTSD was, on average, associated with a higher number of prior traumatic experiences overall.\n\n\nConclusions\nIn one state in the USA, rates of trauma experiences and PTSD among probationers with other mental illnesses are high. Relative to prisoners, little is known about the mental health needs among probationers, so replication in a larger sample across jurisdictions would be useful. Findings are likely to have implications for form of service delivery as well as treatment needs.\n\n"]