OBJECTIVE: The objective was to develop a predictive screener that when given soon after injury will accurately differentiate those who will later develop depression or posttraumatic stress disorder (PTSD) from those who will not. METHOD: This study used a prospective, longitudinal cohort design. Subjects were randomly selected from all injured patients in the emergency department; the majority was assessed within 1 week postinjury with a short predictive screener, followed with in-person interviews after 3 and 6 months to determine the emergence of depression or PTSD within 6 months after injury. RESULTS: A total of 192 completed a risk factor survey at baseline; 165 were assessed over 6 months. Twenty-six subjects [15.8%, 95% confidence interval (CI) 10.2-21.3] were diagnosed with depression, four (2.4%, 95% CI 0.7-5.9) with PTSD and one with both. The final eight-item predictive screener was derived; optimal cutoff scores were ≥2 (of 4) depression risk items and ≥3 (of 5) PTSD risk items. The final screener demonstrated excellent sensitivity and moderate specificity both for clinically significant symptoms and for the diagnoses of depression and PTSD. CONCLUSIONS: A simple screener that can help identify those patients at highest risk for future development of PTSD and depression postinjury allows the judicious allocation of costly mental health resources.