Currently there are no clearly-defined systemic therapies for this bone disease. Small, uncontrolled trials using the second generation bisphosphonate, pamidronate, suggest that bisphosphonates may be effective. This study is a phase 2, controlled, double blinded trial of the third generation oral bisphosphonate, alendronate for the treatment of fibrous dysplasia. We propose to show that treatment with alendronate will improve bone quality, decrease bone pain, decrease fractures, and, if the patient is referred to the companion bone grafting protocol, will allow for the regeneration of better quality bone.