Objectives/Goals: We advance multimodal modeling, including digital twins (DTs), within an AI-enabled Learning Health System (LHS) to turn healthcare data into insights for precision care and translational science. DTs are dynamic patient models integrating EHRs, neuroimaging, biomarkers, wearables, and other real-world data (RWD) tools. Methods/Study Population: Multiple sclerosis (MS) provides a compelling use case of heterogeneous manifestations including fatigue, mobility deficits, cognitive deficits, and sleep disturbance, requiring multimodal integration to capture complexity. DTs integrate EHR, neuroimaging, biomarkers, wearable, and other RWD via ETL pipelines using standards like FHIR, OMOP, and DICOM. Modeling uses ensemble learning, LSTM/DBNs, dimensionality reduction, and bias auditing. Explainable AI (XAI) provides transparency through counterfactual “what if” analyses, such as testing whether risk changes if a patient improves gait speed, adjusts therapy, increases sleep duration, or lowers biomarker levels. Continuous monitoring detects model drift, ensuring reliability per FDA V3: verification, validation, vigilance. Results/Anticipated Results: A robust extract–transform–load (ETL) pipeline maps these inputs into standards such as Fast Healthcare Interoperability Resources (FHIR), the Observational Medical Outcomes Partnership (OMOP) common data model, and the Digital Imaging and Communications in Medicine (DICOM) format, ensuring interoperability and reuse across sites. Development emphasizes robustness through parameter optimization, ensemble learning, prevention of data leakage, preprocessing, dimensionality reduction, and regularization. Key AI applications include MRI lesion and atrophy segmentation with nnU-Net, temporal deep learning for longitudinal forecasting with deep belief networks (DBNs) and long short-term memory (LSTM) models, ensemble modeling to improve generalizability, and bias auditing to promote fairness. Discussion/Significance of Impact: This initiative advances digital health, neuroinformatics, and precision medicine for MS and other complex diseases. Aligned with NIH ODSS Data COUNTS and FDA V3, the framework supports discovery, regulatory science, and generalization to other variable conditions.