The vertebrate musculoskeletal system is essential for the support and movement of the body. To enable a wide variety of movements, the musculoskeleton is complex, consisting of more than 200 muscles attached via muscle connective tissue and tendons to bones. The broad aim of our laboratory is to understand the molecular mechanisms and tissue interactions necessary to pattern and assemble the musculoskeletal system during development and also their role in regeneration and disease. We focus on the muscle connective tissue because it is critical for the form and function of the musculoskeleton, muscle development and regeneration, and defects in muscle and its connective tissue result in devastating congenital muscular dystrophies. Using the chick and mouse model systems, we are using gain and loss-of-function experiments to test the role of muscle cells, connective tissue fibroblasts, and various signaling pathways in mediating the interactions between muscle and connective tissue.