Studies suggest that perievent panic attacks are predictive of future posttraumatic stress disorder (PTSD). Using a population of New York City residents interviewed after the World Trade Center Disaster, the authors measured event exposure, perievent panic, potential confounding, mediating variables, and PTSD. When they estimated a structural equation model, with other stressor events, psychological resources, and Year 1 and Year 2 PTSD as latent variables and adjusted for confounders, the association between perievent panic and Year 2 PTSD was not significant. Results revealed that perievent panic was predictive of Year 1 PTSD, but not Year 2 PTSD. Year 2 stressors and Year 2 psychosocial resources were the best predictors of Year 2 PTSD.