Mental health clinicians are often asked to evaluate prognosis in individuals with posttraumatic stress disorder (PTSD) in clinical, administrative, and legal contexts. Although chronicity of PTSD has been addressed in a number of trauma studies, the data have not been integrated into a coherent approach to the assessment of prognosis. In this paper, the peer-reviewed PTSD literature is surveyed to assist clinicians in making informed prognostic evaluations of the course of PTSD in adults. Potential risk factors, grouped into 11 categories (PTSD stressors, PTSD symptoms, current comorbidity, lifetime comorbidity, childhood separation and abuse, demographics, life stressors, family history, support, treatment, and functional impairment), are reviewed. Knowledge of these risk factors, and of factors associated with chronic PTSD, is helpful in assessing the potential for or degree of chronicity present at the initial evaluation of the patient, as well as in measuring treatment response during the course of therapy. Early identification and the appropriate treatment and management of remediable risk and associated factors may help prevent the development of chronic PTSD. Longitudinally assessing the response of treatable risk factors should provide an additional means for evaluating prognosis. A PTSD Prognostic Checklist, which rates risk and associated factors in each category, is proposed. Validity and reliability have not yet been established for this instrument. It is hoped that clinicians will use and conduct research on it as an initial step toward advancing its scientific utility.