Patients 4 years of age and older with bone lesions that are highly likely to cause significant pain and illness may be eligible for this 2-year study. Participants must be simultaneously enrolled in NIDCR's research protocol 98-D-0145 (Screening and Natural History of Patients with Polyostotic Fibrous Dysplasia and McCune-Albright Syndrome) or 98-D-0146 (A Randomized, Placebo-Controlled Trial of Alendronate in the Treatment of Polyostotic Fibrous Dysplasia and McCune-Albright Syndrome).