Background: Recent attention has begun to be focused on the effects of disaster recovery work on nonrescue workers. The goal of this study was to assess the prevalence and predictors of posttraumatic stress disorder (PTSD) and related symptoms in a population of utility workers deployed to the World Trade Center (WTC) site in the aftermath of 9/11. Methods: Utility workers deployed to the WTC site were screened at their place of employment between 10 and 34 months following the WTC attacks, utilizing both structured interviews and self-report measures. PTSD symptoms were assessed by the CAPS and the PCL; co-morbid disorders were also assessed. 2,960 individuals with complete CAPS and PCL data were included in the analyses. Results: Eight percent of participants had symptoms consistent with full PTSD, 9.3% with subthreshold PTSD, 6% with MDD, 3.5% with GAD, and 2.5% with panic disorder. Although risk factors included psychiatric and trauma history, 51% of individuals with probable PTSD had neither; subjective perception of threat to one's life was the best predictor of probable PTSD. Extent of exposure predicted 89% of PTSD cases in those without a psychiatric or trauma history, but only 67% of cases among those with both. Conclusions: Nonrescue workers deployed to a disaster site are at risk for PTSD and depression. Extent of exposure affected the most vulnerable workers differently than the least vulnerable ones. These results suggest that the relationship among predictors of PTSD may be different for different vulnerability groups, and underscore the importance of screening, education, and prevention programs for disaster workers. Depression and Anxiety 28:210–217, 2011. © 2010 Wiley-Liss, Inc.