Embryonal rhabdomyosarcoma (ERMS) is a soft tissue cancer with features of skeletal muscle, and the most common soft tissue connective cancer of childhood. While the medical community has made great strides in improving care and cure for children with ERMS, there remains a group of children with high-risk disease who only survive their cancer about one third of the time. To develop new treatments for these children, it is important to understand what mutations their ERMS tumors carry.