It is difficult to determine predisposing factors for posttraumatic stress disorder (PTSD) in retrospective studies because the illness can influence patients’ perception or recollection of pretrauma characteristics. Heinrichs et al. (p. 2276) circumvented this problem by testing healthy probationary firefighters just after basic training and again 6, 9, 12, and 24 months later. At 24 months, 16% of the men met the criteria for PTSD. No psychological or biological variable except body weight changed significantly over time. However, high scores for PTSD symptoms at 2 years were predicted by greater baseline hostility and lower self-efficacy, i.e., self-perceived competence. Firefighters with these two high-risk characteristics at job entry showed a general increase in all psychological symptoms (e.g., PTSD, depression, anxiety, alexithymia) over the 2 years. Hostility and self-efficacy may therefore be informative measures in populations at high risk for trauma-related disorders and could be addressed through coping skills training.