Department of Veterans Affairs Health Outcomes of Military Exposures Epidemiology Program 1. Title: Longitudinal Study of Post 9/11 Veterans 2. Purpose : Health Outcomes of Military Exposures (HOME) is conducting a follow up health survey on cohorts of Post 9/11 Deployed Veterans and Post 9/11 era Veterans (those who served during the same time but did not deploy). Results from this study will improve our understanding of the long-term health consequences of military deployment and the health services that Post 9/11 Veterans need. The findings will also help influence policy and benefits for these Veterans. 3. Background: This task will be the second data collection from two cohorts of post 9/11 Veterans who were identified for participation in either the National Health Study for a New Generation of U.S. Veterans (NewGen) or the Comparative Health Assessment Interview (CHAI) Research Study. The initial data collection for NewGen was conducted in 2009-2010 and the CHAI data collection was in the field in 2018; each study surveyed a population-based sample of military Service members with DoD service between October 2001 and June 2008, and October and March 2015, respectively. This data collection will return to the original populations and include a sample of Service members with service after JUNE 2015 (the date on which the CHAI sampling frame was closed). 4. Scope: This study will consist of 1) a request to complete a questionnaire on a variety of health topics via web and telephone (the sample size will not exceed 100,000); and 2) simple and complex data analysis of information collected on the questionnaire. 5. Period of Performance : Three Years 6. Place of Performance: The contract services and activities will take place at the contractor's place of business. Weekly meetings between the contractor and HOME will take place virtually