We propose a longitudinal study of the natural history of types III and IV osteogenesis imperfecta for children age birth to 25 years. A consistent objective throughout this study is to obtain a comprehensive assessment of the natural history and progression of the multiple secondary features of osteogenesis imperfecta. In addition to radiographic, bone density, physical rehabilitation and dental manifestations, we will assess the cardiovascular, pulmonary, neurological, and audiology systems.