ABSTRACT The proposed project aims to address the challenges faced by approximately 30 million individuals in the United States with undiagnosed or rare diseases by extending best practices from the Undiagnosed Diseases Network (UDN) model. We seek to enhance access to evidence-based diagnostic, research, and care practices, especially for historically underserved populations, through implementation science frameworks. Specific aims include developing a framework for a learning health network, increasing access for underserved communities, leveraging advanced technical solutions to enhance diagnosis and care, and ensuring continuity of care for participants awaiting diagnosis. Methods involve evaluating implementation science frameworks, gathering participant perspectives through qualitative methods, developing technical solutions, and supporting ongoing research studies. Long-term objectives include integrating UDN methods into broader clinical practice and improving outcomes for individuals with undiagnosed and rare diseases.