The current proposal seeks to develop an infrastructure for resource, tool and data sharing in the field of stroke in India, modeled after te existing NIH funded stroke infrastructure in USA. Our goal is to lay the foundation for Indo-U.S. research collaborations for comparative studies on stroke risk factors, outcomes, future genetic and imaging studies, and stroke clinical trials. Over the past decade the U.S. NIH has recognized the importance of pooling advanced clinical, imaging, laboratory and genetic data from multiple centers in order to address major questions in the field of stroke. NIH funding has helped to create several large stroke databases that have stimulated collaborative research. Examples include the Stroke Genetics Network (SiGN), the Stroke Imaging Repository (STIR), and the Specialized Program of Translational Research in Acute Stroke (SPOTRIAS). The Massachusetts General Hospital (MGH, the U.S. site of this proposal), has been contributing data to each of these registries and networks. In fact, the PI and co-investigators on this proposal have played key roles in their development. We have gained experience in critical database framework issues such as definitions, queries and logic checks, data storage/retrieval, and have developed tools for stroke phenotypic, genetic and imaging data analysis, and stroke subtyping. The advantages of collaborative databases have also been recognized in India. Our Indian Co-PIs from 5 high-volume geographically diverse centers have created local registries and contributed data towards national and international efforts, e.g. the hospital-based stroke registry at SreeChitra Institute Kerala, the population- based Ludhiana stroke registry, and the ICMR and SITS-SEARS registries. Currently, these databases lack multi-ethnic data, and are limited by issues such as varying data definitions and non-standardized methodology. These shortcomings, and the potential to uncover new biological insights, were highlighted in our recent study comparing young stroke at MGH versus two Indian sites (AIIMS, Nizam). We now propose a comprehensive Indian stroke registry, with data definitions and data fields consistent with existing NIH registries (e.g. SiGN). Training a group of research associates and fellows on methods of data acquisition and entry is a key component and will allow this initial effort to be sustained. The user-driven web-based platform will allow research teams to share and compare multi-ethnic data, and accelerate the pace of stroke clinical, genetic and imaging research around the world.