ABSTRACT - RESOURCE CORE The American Joint Replacement Registry (AJRR) is part of the American Academy of Orthopedic Surgeons (AAOS) Registry Program, and is the Resource Core of the Mayo Core Center for Clinical Research in Total Joint Arthroplasty (CORE-TJA). The AJRR currently captures about 25-30% of all hip and knee TJA procedures in the United States. The AJRR will enhance the clinical research capabilities of the TJA research community by providing access to nationwide registry data and implementing novel data collection and data analysis methodologies to facilitate TJA research in large linked databases and clinical research networks. The Specific Aims of the Resource Core are: (1) To work collaboratively with the CORE-TJA Methodology Core in design, protocol development, statistical analysis and conduct of TJA studies using the AJRR datasets, (2) To test the transportability and external validity of TJA-specific natural language processing (NLP) algorithms (developed by Methodology Core) in hospitals within the AJRR network, and (3) To participate in pilot & feasibility studies within the CORE-TJA network and to develop data and analytical standards for use of AJRR data in partnership with academic institutions and clinical research networks. The availability of TJA-specific data from the AJRR, enriched with linked databases and access to EHR data in clinical research networks will offer tremendous research opportunities and exert a sustained, powerful influence on future TJA clinical research landscape.