The primary purpose of this study is to determine whether gross motor proficiency of children and young adults with hemophilia falls below average, sex-specific normative data, using the standardized motor assessment the Bruininks-Oseretsky Test of Motor Proficiency, Second Edition (BOT-2™). The primary hypothesis is that children and young adults with hemophilia perform at a lower level of gross motor proficiency compared to same-aged peers, despite advances in care.