PROJECT SUMMARY/ABSTRACT Metabolic associated steatotic liver disease (MASLD) and metabolic associated steatohepatitis (MASH) represent a major cause of liver disease morbidity and mortality. The NASH Clinical Research Network (NASH CRN) has been sponsored by the NIDDK since 2002 and is an international leader in clinical studies in MASH. The overarching objective of this application is to pursue clinical and translational research in MASH that will ultimately lead to improvement in the management of patients with MAFLD and MASH. There remains a need to understand the burden of liver disease and other causes of morbidity and mortality in MASH. New medications for adults with MASH are currently in clinical trials but no therapies are currently in development for children. Thus, there is a need for the NASH CRN to continue our leadership in describing the natural history of MASLD and MASH and to continue our pioneering work in design and implementation of clinical trials for MASH. This application is for the continuation of the Seattle Clinical Center of the NASH CRN, which has been part of the NASH CRN since its founding in 2002 and represents a large geographic area with a unique patient population. Several specific aims are proposed that will advance the objectives of the NASH CRN during the next period of funding. We will complete enrollment and follow up of MASLD and MASH patients in the adult and pediatric Database study and VEDS clinical trial. We will focus the latter part of the final 3-year period completing data analyses and publishing high-impact papers. The PI and Seattle Clinical Center have been leaders in the NASH CRN since its inception, and we remain fully committed to ensuring the success and impact of this network in improving liver health and advancing the mission of the NIDDK.