ABSTRACT The World Trade Center (WTC) Health Registry, the largest post-disaster registry in U.S. history, is among the world’s longest running as it continues to track long-term health impacts of the 9/11 disaster among a diverse cohort of over 71,000 persons who performed 9/11-related rescue/recovery work (responders), or who lived, worked or attended school in lower Manhattan on 9/11/2001 (survivors). The Registry’s 142 peer-review publications to-date contribute substantially to the literature on 9/11 physical and mental health outcomes and gaps in care and inform 9/11 healthcare policy and clinical practice. The Registry also conducts extensive outreach to refer enrollees to the WTC Health Program (WTCHP) and provides de-identified survey data and recruitment services for 9/11-related research by independent or collaborative external researchers. This renewal will enable the Registry to extend its epidemiological research and surveillance 24 years post- 9/11 via follow-up health surveys and in-depth studies, including cancer and mortality assessments and in-depth studies with WTCHP entities to identify potential emerging health conditions. We propose 5 specific aims: (1) Maintain the Registry as a public health resource to allow health professionals to track and investigate possible trends in illness and recovery (i.e., maintain updated contact information for enrollees, keep them engaged); (2) Expand knowledge about long-term health effects of 9/11 by facilitating medical, public health, emergency preparedness or other research relevant to the WTC Health Program with emphasis on impacts to the WTC survivor cohort (i.e., continue matches to vital records, cancer registries and hospitalization data; extend cancer/mortality assessments 20 years post-9/11; conduct a Wave 6 survey to ascertain cohort health status 23-24 years after 9/11; conduct qualitative research to better understand persistence of 9/11 conditions and their mitigation; assess the contribution of 9/11 exposure and other risk factors to the course of health conditions, functional impairment, age-related conditions, and unmet healthcare needs); (3): Conduct community activities to respond to the physical and mental health concerns and specific healthcare needs of enrollees and others exposed to 9/11 (i.e., disseminate Registry findings and recommendations to enrollees, the public, and WTCHP leadership via video, social media, e-newsletters, website; provide data and other resources to enrollees and the public; continue health promotion activities); (4): Maintain the 9/11 Treatment Referral Program to help enrollees and others find care for 9/11-related health problems (i.e., inform enrollees of 9/11-related services, conduct outreach to assist them in applying to the WTCHP, including those with specific conditions or unmet care needs); and (5): Collaborate with WTCHP entities to explore surveillance signals and treatment outcomes including 9/11 linkage with uncommon health condi...