The primary objective of this project is to capitalize on a variety of existing data sources by integrating and analyzing them in novel ways to answer key questions related to the chronic effects of mild traumatic brain injury (mTBI) in Veterans over time. Although prior studies have found that moderate and severe TBI are associated with a variety of adverse clinical outcomes, the effects of mTBI are less well understood. We propose to address this gap in knowledge through four complimentary Specific Aims. In Aim 1, we propose to examine the association between mTBI and important shorter-term clinical outcomes such as accidents and injuries in Veterans from recent conflicts in Iraq and Afghanistan, focusing on identifying factors associated with resilience and the potential benefits of adequate treatment. In Aim 2, we propose to expand these analyses to include Veterans from all eras and to study longer-term clinical outcomes including neurosensory disorders and mortality, focusing on the potential confounding effects of comorbid medical conditions and the impact of their treatment. In Aim 3, we propose to identify different trajectories of mTBI-related comorbid burden, with the goal of identifying factors associated with being in low and high distress trajectories. Finally, in Aim 4, we propose to lay the groundwork for future analyses using more detailed and unified mTBI data by developing the groundwork to create a National CENC Data Repository (NCDR). Together, these Aims will advance our knowledge of the effects of mTBI on important clinical outcomes in Veterans of all ages and eras in a highly efficient manner and will provide insight into potential strategies for prevention and intervention.