This double-blind randomized controlled trial was conducted from January 2011 to February 2014. To acquire a diverse sample, outpatients were recruited at an academic medical center and at a private mental health clinic with primarily Spanish-speaking patients. A single team of investigators conducted the trial at both settings. Individuals with chronic PTSD were randomly assigned to 24 weeks of double-blind treatment with sertraline plus mirtazapine or sertraline plus placebo. This study was conducted in compliance with the Code of Ethics of the World Medical Association (Declaration of Helsinki) and the standards established by an Institutional Review Board and by the National Institutes of Health. Informed consent was obtained from participants after the nature of the procedures was explained.