The 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. 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. These longitudinal studies of participants with TBI present an opportunity to accurately categorize this risk by harmonizing the overlapping elements from two or more VA-funded resources. 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. Recent advances in FAIR (Findable, Accessible, Interoperable, Reusable) data methods can guide these efforts and ensure efficient and accurate results with large and similar enough data. Our multiple-investigator proposal team has identified two longitudinal cohort studies that can address the above-mentioned Post-traumatic Brain Health knowledge gaps in the relatively near term. Longer-term prospects from this work include incorporation of other potential largescale datasets that can be added once the initial harmonization and FAIR data methods development are established. 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, and 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. Our proposed leadership team has experience pooling and harmonizing data from large studies that measure similar concepts with a variety measurements and disparate variable names. We have developed a model data harmonization system to combine data from multiple heterogenous studies and facilitate the analysis of a single pooled dataset. The system combines study files into a single data model and leverages natural language processing techniques to facilitate data pooling and harmonization using algorithmic approaches. Notably, this team's preliminary success resulted in being the first and only team to create and disseminate FITBIR metadata and re...