This study will evaluate the effect of pamidronate a drug that decreases bone resorption (breakdown) on osteogenesis imperfecta. This is a genetic disorder of collagen, the major protein in bone. The abnormal collagen causes weak bones, and children with severe osteogenesis imperfecta sustain many fractures throughout their lives. They also have growth deficiency, curvature of the spine, crumbling teeth, hearing loss, easy bruising and heart and lung problems. The study will compare bone density, quality and strength, final adult height, trunk height, and functional ability in children who receive 1) pamidronate every 3 months, 2) pamidronate every 3 months + growth hormone injections, 3) pamidronate every 6 months, or 4) pamidronate every 6 months + growth hormone injections. Children 2 years of age and older with severe osteogenesis imperfecta (types III and IV) may be eligible for this study. Those enrolled will be randomly assigned to groups according to age; children two to four years of age will be randomly assigned to receive pamidronate every 3 or every 6 months. Children four years of age and older may participate in the growth hormone treatment groups. These children will continue on growth hormone until they reach their adult height or fail to grow as much as would be expected for someone on growth hormone. Patients will be followed in the clinic every 3 months for a history, physical examination, X-rays, blood tests, and measurements (weight, head circumference, and bone lengths). Children will receive a 3 to 4 hour infusion of pamidronate through an intravenous catheter (thin flexible tube placed in a vein) once a day for 3 days each visit. (Once inserted, the catheter is left in place to avoid multiple needle sticks for administering the drug and collecting blood samples.) Children who are taking growth hormone will be given the drug at the first treatment visit. At that time, the accompanying parent will be instructed on how to mix the drug and give injections. The child receives an injection 6 days a week (Sunday off).