The Muscle Phenotyping and Imaging Core serves as a resource for both muscle biologists and other life scientists to employ a variety of assessment tools for the study of muscle phenotypes. With advances in technologies to create genetically engineered mice, the need for expertise in muscle biology has grown, as unanticipated muscle phenotypes have resulted from ablation of target genes. Since non-muscle researchers lack the necessary experience, training and technical instrumentation to accomplish this goal, the Muscle Phenotyping and Imaging Core fulfills a void that provides a useful resource, which allows nonmuscle biologists to capitalize on available expertise, specialized protocols and instrumentation. Furthermore, by lowering barriers for non-muscle scientists to carry out muscle-related studies, by providing education and an ecosystem of scientists and activities focused on muscle biology, the Core attract new scientists to the muscle field. Moreover, technological advances now permit the production of vast libraries of small molecules with potential therapeutic applications, and enable high-throughput, robotic, functional invitro analysis, to identify drugs to target focused pathways. The High-throughput Screening and Cell Repository Core (Core B) ofthis application, along with the resources of the UCLA Molecular Screening Shared Resource (MSSR) provides screening capabilities to UCLA investigators interested in finding treatments for neuromuscular diseases. A major challenge for translational research lies in the extension of these in vitro findings to complex mammalian systems in vivo, where experimental outcomes may differ importantly from observations made on single cell types. This Core provides a means for investigators to test lead therapeutic compounds in mice and evaluate the effect of these compounds on muscle pathology and function. In addition to assessing muscle phenotypes using traditional approaches, the Core emphasizes the development of innovative, non-invasive methodologies, which provide unique resources to investigate physiological oiJtcomes in longitudinal studies.