The traumatic brain injury (TBI) literature provides preliminary evidence supporting associations between TBI exposures and poor health and functional outcomes, particularly as they occur in the context of the traumatic and stressful circumstances of military deployment. There is still much to be understood, however, regarding the associations of patient and injury characteristics with the prognosis of psychological health, physical health, functioning, and quality of life outcomes. TBI has been a priority research area among veterans and military service personnel due to its high prevalence in these populations. Ongoing longitudinal cohort studies of service members and veterans with military combat and training exposures offer researchers access to extant data addressing factors that modify risks for developing and/or recovering from a range of brain disorders, including TBI, PTSD, pain, depression, and suicidality. Pooling individual participant level data from longitudinal TBI research studies will result in a large enough dataset to consider relevant moderators, mediators, and confounders in analyses and allow for more impactful and clinically meaningful findings. In order to address the present knowledge gaps and harmonize largescale, multi-modal data from varied sources, well-planned and reproducible standardization, curation, and dissemination is needed to allow for meaningful analyses. The Long-term Impact of Military-relevant Brain Injury Consortium's Prospective Longitudinal Study (PLS) is a 10-year, 17- site cohort of >2,500 service members and veteran participants with combat-exposure who are well-characterized initially and then have annual reassessments. The Translational Research Center for TBI and Stress Disorders is a 14-year, 2-site longitudinal cohort of >925 veterans with combat-exposure who are deeply characterized initially and then undergo comprehensive reassessment at 2, 5 and 10 years. These two ongoing, prospective, longitudinal cohorts of active duty and veteran service members offer access to a wide range of potential risk factors that can affect response to care and outcomes including demographics (age, sex, race, ACEs, SDOH), injury characteristics (pre-exposure factors, exposure factors), biomarkers including genetics and epigenetics (serum, saliva, brain imaging, evoked potentials), and functional measures (functional neuroimaging, EEG, computerized posturography, computerized eye tracking, special senses testing, clinical examination, neuropsychological assessments, symptom questionnaires). While there is considerable overlap across the LIMBIC and TRACTS cohorts' data elements, considerable harmonization of the tools used and data obtained is needed to allow for valid and meaningful analyses across cohorts. Additionally, a standardized and robust approach to the clinical translation of the data to actionable risk stratification and/or clinical utility is necessary. For this proposal, the researchers will work to ...