PROJECT SUMMARY Posttraumatic stress disorder (PTSD) can be debilitating and is related to impaired occupational and social functioning, chronic medical problems, disability, and increases in suicidality, violence, and criminal behavior. Over 10 million Americans are treated annually for sudden, severe illnesses or injuries that require very urgent treatment; and an estimated 20% of hospitalized traumatic injury patients have persisting mental health problems. Identifying those at risk for later disorder is difficult, and no screens can accurately predict PTSD in Americans exposed to traumatic stress. In research on adults exposed to traumatic injury, theory-driven pre- trauma, time-of-trauma, and post-trauma risk factors were strongly related to outcomes and accurately identified those who later had elevated PTSD symptoms. We propose to extend our work to a population level to create a screen for use in U.S. hospitals. In diverse populations of sudden illness or injury patients at hospitals sites in Baltimore, MD, Akron, OH, and Palo Alto, CA, data will be collected on theory-driven, highly predictive pre-trauma (gender, education, socioeconomic status, ethnicity/race, childhood home life and parental dysfunction, past trauma exposure); time-of-trauma (trauma intensity, pre-trauma home life; pre- trauma life stress), and post-trauma (acute PTSD and dissociation symptoms, negative thinking; post-trauma life stress; post-trauma social support; post-trauma social constraints) risk factors and later symptoms of disorder in 1,500 patients, including 1,100 (76%) ethnic/racial minorities. Data will also be collected on five variables found to relate to disparities in mental health or PTSD: discrimination/racism, competing needs, community cohesion, stigma, and negative expectations about treatment. Data collected will include sufficiently large samples of African American, Latino, Asians, and mixed ethnicity/race patients for separately analyses for these groups. Relationships of all predictors and disparities variables to outcomes and covariance among predictors and disparities variables will be examined to select risk factor and disparities variables that are highly predictive, similarly related to outcomes across subgroups, and can be measured with the fewest items and items that are briefer and less personal, stigmatizing, and difficult to understand. In Wave II of data collection, predictive performance will be assessed in a new sample of 1,500 patients, including 1,100 (76%) ethnic/racial minorities with a goal of identifying at least 80% (sensitivity) of those who later have high PTSD symptoms and at least 70% (specificity) of those who recover well.