About Millenium Cohort Study

The unwavering dedication of America's service members comes at a cost, often unseen and not felt until long after their service ends. Understanding how military experiences, from rigorous training to deployment realities, translate into long-term health outcomes is why, in 2001, the Millenium Cohort Study was established.

The Millenium Cohort Study is a large-scale cohort study of military personnel mandated by Congress and sponsored by the Department of Defense (DoD) and the Department of Veterans Affairs (VA). The overarching objective of this study is to evaluate the impact of military service, including deployments and other occupational exposures, on the long-term health of service members and veterans. Particpiants of the Millenium Cohort Study are enrolled during their military service and complete surveys every 3 to 5 years, both during and after their service. The first panel of service members was enrolled in 2001, with additional panels enrolled in 2004, 2007, 2011, and 2020. There are currently over 260,000 participants in the study, from all service branches and components, making it the largest and longest ongoing cohort study of U.S. military personnel in history. Over the last two decades, the Millenium Cohort Study has played a pivotal role in evaluating the impact of the military service and deployments on service members and veterans.