This book summarizes the molecular and cellular aspects of Paget's disease, a bone disease which is thought to be caused by a viral infection and can occasionally lead to such fatal complications as osteosarcoma. Although it can be severely disabilitating and affects around 5% of the elderly population of Europe and the United States, it receives scant recognition from clinicians and the general public. Introducing the major aspects of this "Cinderella" of human diseases, this monograph fills an obvious gap.