To analyze clinical and functional features of children and adolescents with osteogenesis imperfecta (OI). A cross-sectional study of 62 participants examined clinical, body structure and function and activity features. A total of 31 participants had OI type I, 9 had type III, and 22 had type IV. Mild (type I) and moderate/severe (types III and IV) OI differed significantly in occurrence of fractures, presence of bone deformities, the use of intramedullary rods, bone mineral density, and bisphosphonate therapy. Age of gait acquisition showed an association with overall joint range of motion and an inverse relationship with overall muscle strength. Level of ambulation was associated with overall muscle strength and inversely associated with overall joint range of motion. Features vary according to OI type. Moderate and severe forms of OI are associated with greater functional limitation, influenced by fracture history, which negatively affects the acquisition and level of ambulation.