The purpose of this longitudinal cohort study is to assess prevalence and correlates of medium-term and long-term psychological distress among residents of the New York City (NYC) metropolitan area in response to the World Trade Center disaster (WTSD). This study plans to extend a baseline assessment and recruiting interview that will take place on March 2002 with two further survey waves in September 2002 and September 2003. Previous post-disaster research suggests that 4-5% or more of all residents of NYC may have chronic Post-Traumatic Stress Disorder (PTSD) 6 months after the incident; this would represent 400,000 New Yorkers. Given the density of NYC and the unparalleled human and financial losses resulting from the WTCD, the prevalence of psychological distress among residents of the NYC metropolitan area may be even higher The scope of the WTCD in NYC presents a unique opportunity to assess hypotheses that have previously been formulated through research after smaller disasters and to guide future disaster planning and response. This research will provide estimates of the changing prevalence of psychological distress (particularly PTSD, anxiety, and depression) in the NYC metropolitan area. We will assess the prognostic role of correlates of psychological distress including event experiences (e.g., distance from WTC), demographics (e.g., age, gender, race/ethnicity, occupation), socio-economic factors (e.g., socio-economic status, social support); lifetime traumatic events, past victimization, past exposure to stressors and trauma, acute emotional events, and commonly occurring co-morbidities (e.g., substance use). We will also inventory the changing availability of mental health and health care services related to post-WTCD sequelae and measure service utilization and perceived organizational responsiveness in the medium- and long-term. In order to answer these questions a cohort of persons living in the NYC metropolitan area (divided into four zones radiating concentrically from the WTC site) will be recruited through random digit dialing in March 2002. This proposal pertains to the follow-up waves 2 and 3 of this cohort. We will administer well validated diagnostic survey measures to respondents at baseline and in follow-up. We will recruit 2,670 persons for this study at baseline (and expecting 25% attrition over a 2 year period; i.e., n=2000 for final cohort). We will use multivariable analyses and hierarchical modeling to address key research hypotheses in this proposal.