Although anger is an important feature of posttraumatic stress disorder (PTSD) it is unclear whether it is simply concomitant or plays a role in maintaining symptoms. A previous study of disaster workers responding to the terrorist attacks of September 11, 2001 (Evans et al., 2006) indicated that those with PTSD evidenced more severe anger than those without. The purpose of this study was to conduct a 1-year follow-up to assess the role of anger in maintaining PTSD. Workers with PTSD continued to report more severe anger than those without; there were statistically significant associations between changes in anger, PTSD severity, depression, and psychiatric distress. Multiple regression analysis indicated initial anger severity to be a significant predictor of PTSD severity at follow-up, which is consistent with the notion that anger maintains PTSD. One implication is that disaster workers with high anger may benefit from early intervention to prevent chronic PTSD.